feat(vegas): let live content keep its place in the ticker (#457)

* feat(vegas): let live content keep its place in the ticker

Live content used to preempt Vegas outright: while any plugin reported
live priority the display controller refused to run the ticker at all and
showed a full-screen scoreboard instead. Keeping the marquee meant not
seeing live scores; seeing live scores meant losing the marquee.

Two changes, both off by default.

vegas_scroll.live_in_ticker keeps the ticker running through a live game.
Three places assumed the takeover and all three now honour it: the
controller's gate, the coordinator's per-frame pause, and the rotation
switch that would otherwise move current_mode_index underneath a ticker
that never yields.

And the rotation is no longer a strict round robin. It was one slot per
plugin per cycle, so with a dozen plugins enabled a live score came round
once a lap and could be minutes old on screen. A plugin can now hold
several slots, placed by Smooth Weighted Round-Robin -- the same
scheduler the sports plugins already use to rotate their own games. The
property that matters is that repeats are spread through the cycle
rather than clumped: three in a row and then silence would be worse than
no boost at all.

Weight comes from the plugin first, via a new optional
get_vegas_priority_weight(), then from the core: live content earns
live_weight, everything else 1. So existing plugins gain the behaviour
without changes, and the hook exists for the one thing the core cannot
work out -- the core can see that a game is live but not whose, so only
the plugin can say a favorite is playing.

Documented in ADVANCED_FEATURES (worked example, why weights are per
plugin not per game, and that frequency is not freshness),
CONFIG_REFERENCE, PLUGIN_API_REFERENCE, and the config template.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Udr6MfaFLUPhX5Fgo67Jf5

* fix(vegas): carry the new keys through config, and correct two docs

Three findings from CodeRabbit, all valid.

to_dict() and update() enumerate keys explicitly and had not learned the
three new ones, so get_status() never reported them and a live config
change never applied -- turning live_in_ticker on in the web UI would
have done nothing until a restart. update() clamps the weights exactly
as from_config does.

The vegas_scroll key count in ADVANCED_FEATURES said 29; the template
has 30. My arithmetic, not the reviewer's.

The third was a documentation error rather than a code one, and I have
fixed it the other way round. The docs claimed a raising
get_vegas_priority_weight() is treated as weight 1. The code instead
falls through to the core's own live-content check, and that is the
better behaviour: the hook is only how a plugin asks for *more* than
live_weight, and has_live_priority/has_live_content are separate methods
guarded separately, so a plugin with a broken weight calculation should
lose the favorite distinction and keep the live boost. Said so in the
code, the base-plugin docstring and the API reference.

The test fake now fails in each place independently, because the two
failures mean different things: a broken hook still earns live_weight, a
plugin that cannot say whether it is live has nothing to fall back on
and weighs 1.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ui/code/session_01Udr6MfaFLUPhX5Fgo67Jf5

* fix(vegas): stop the heaviest plugin doubling across the cycle seam

Smooth Weighted Round-Robin spaces repeats well within a pass, but it
schedules the heaviest item first and usually last as well. The strip
loops, so those two are neighbours: the marquee showed the same plugin
twice running at exactly the one join a within-cycle check cannot see.
Observed on a live rig at 28 slots -- gaps of 6, 7, 7, 7 and then 1.

Rotating the list does not fix it. Rotation preserves the cyclic order
exactly, so it moves where the seam is drawn rather than the adjacency
itself; the trailing entry has to be swapped with one from the middle.

The first version swapped with the first slot that merely fitted, which
undid the spacing this exists to protect -- it moved a repeat from a gap
of 7 into a gap of 2, more clumped than the seam had ever been. It now
picks the candidate furthest from any other appearance, so the repeat
lands in the widest gap.

Left alone when no candidate exists. A plugin holding most of the slots
has to neighbour itself, and scheduling it is better than refusing to.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Udr6MfaFLUPhX5Fgo67Jf5

* fix(vegas): stop the seam repair creating the duplicate it removes

Swapping the trailing repeat with a middle slot moves two elements, and
the candidate filter only guarded one of them. It checked the neighbours
`repeated` would acquire at j, but not what the displaced element would
sit beside at the end -- so ['a','b','c','d','x','y','x','a'] came back
as [...,'x','x'], the seam duplicate traded for a fresh one. Reported by
CodeRabbit with that exact case.

Adding the missing condition fixed it and immediately broke something
else: schedule[j] is schedule[-2] when j is the second-to-last slot, so
that candidate was always excluded, and ['a','b','c','a'] lost the only
repair it has. The same class of mistake twice, from reasoning about
which neighbours two moved elements end up with.

So it no longer reasons. It performs each candidate swap, counts the
cyclic duplicates in the result, and keeps the best one that has none --
preferring whichever leaves the boosted plugin most evenly spread. When
no such swap exists the schedule is returned untouched, which is the
unavoidable case: a plugin holding most of the slots has to neighbour
itself.

Fuzzed across 6,956 seam schedules: none made worse, none lost an entry.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Udr6MfaFLUPhX5Fgo67Jf5

---------

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/PLUGIN_API_REFERENCE.md

@@ -170,6 +170,47 @@ Default returns `False`.
 List of display modes to show during a live takeover. Default returns the
 plugin's `display_modes` from its manifest.
 
+#### `get_vegas_priority_weight() -> Optional[int]`
+
+How many slots per Vegas cycle this plugin should get. Default returns
+`None`, which defers to the core.
+
+The Vegas ticker is otherwise a strict round robin — every plugin appears
+exactly once per cycle — so with a dozen plugins enabled a live score can be
+minutes stale by the time it comes round. A weight of *N* gives the plugin
+*N* slots per cycle, spread evenly through it rather than clumped.
+
+**You usually do not need this.** When the hook returns `None`, the core
+already gives a plugin `vegas_scroll.live_weight` whenever
+`has_live_priority()` and `has_live_content()` are both true. Live sports get
+extra turns with no code at all.
+
+Implement it only when the plugin knows something the core cannot. The
+motivating case is favorite teams — the core can see *that* a game is live,
+but not *whose*:
+
+```python
+def get_vegas_priority_weight(self):
+    if not (self.has_live_priority() and self.has_live_content()):
+        return None                       # let the core decide
+    vegas = self.global_config.get('display', {}).get('vegas_scroll', {})
+    if self._favorite_is_live():
+        return vegas.get('favorite_live_weight', 5)
+    return vegas.get('live_weight', 3)
+```
+
+The weight is per *plugin*, not per game: a scoreboard showing four live games
+still occupies one slot at a time and rotates its own games within it. Values
+are clamped to 1–10 by the caller. An exception here is caught and logged, and
+the core then falls back to its own live-content check — so a plugin whose
+weight calculation is broken still gets `live_weight` for a game that really
+is live, rather than being demoted to 1.
+
+Only consulted when the user has set `vegas_scroll.live_in_ticker`. With the
+default (`false`) live content preempts Vegas entirely and there is no ticker
+to be weighted within. See
+[ADVANCED_FEATURES.md](ADVANCED_FEATURES.md#live-content-in-the-ticker).
+
 ### Vegas scroll hooks
 
 Vegas mode shows multiple plugins as a single continuous scroll instead of