feat(common): sports_celebration, sports_fetch and sports_card_wrappers, promoted from the scoreboards (sports consolidation stage 3) (#672)

Three new hardware-free modules holding code the scoreboard plugins carry
as identical copies (executable AST, docstrings stripped, checked across
every carrying plugin at ledmatrix-plugins 30455671). The bodies are the
plugins'; the changes are type annotations for the mypy ratchet, the
colour helpers losing their leading underscore as public free functions,
and two comments that described the plugins' files.

- src/common/sports_celebration.py: SportsCelebrationMixin, the score/win
  takeover drawn by afl, football, hockey, nrl and soccer
  (_draw_celebration_layout and the palette, backdrop, scenery, confetti,
  crest and _fit_font steps, with their class constants), plus the colour
  helpers (logo_palette, lift_color, cap_luminance, mix_color, ...). Only
  the drawing: _start_celebration, _check_for_goal/_check_for_score,
  _check_for_win and display() differ between the plugins and stay there.
- src/common/sports_fetch.py: SportsFetchMixin, the four SportsCore methods
  identical in all nine scoreboards: _fetch_season_directly,
  _background_fetches_espn_ranges, _needs_previous_day and
  _wants_live_odds, with _LOOKBACK_CUTOFF_HOUR and _LIVE_ODDS_LOOKAHEAD.
  _get_timezone, _extract_game_details and _fetch_data are as identical
  and stay behind, for the reasons sports_shared gives (a per-plugin
  import; the abstract contract); so does SportsUpcoming.__init__, since
  no src/common mixin has a constructor.
- src/common/sports_card_wrappers.py: SportsCardWrappersMixin, the
  seventeen sports_card delegations the eight game renderers carry (15 in
  all eight, 2 in all but football, whose own versions override them).
  _schema_font_size/_resolve_font_size look identical but read each
  plugin's own _SCHEMA_PATH, so they stay.

Each mixin has no __init__ and creates no attributes (the host contract is
declared as annotations only), defines no name the mixins beside it
define, and documents the attributes it reads; a host-contract test
parses each and fails on an undocumented read. A method kept on a
plugin's class wins over the mixin's.

Tests: behaviour ported from the plugins' celebration, odds, lookback and
date-range tests against stub hosts carrying exactly the contract, with
crests drawn by the test (test_sports_celebration.py, test_sports_fetch.py,
test_sports_card_wrappers.py), and test_sports_stage3_parity.py, which with
LEDMATRIX_PLUGINS set compares every body with every plugin copy that is
left (58 pass against the plugins today; a copy that is gone counts as
adopted). All three modules are on the mypy ratchet, in
src/common/README.md, the CHANGELOG's Unreleased section and
SPORTS_UNIFICATION's module table. Nothing in core uses them yet.

Full suite: the same 67 failing test ids as main (Windows-only), 77 more
passing.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

src/common/README.md

@@ -38,6 +38,9 @@ Rules for the package:
 | [`scroll_helper`](#scroll_helper) | Pre-rendered horizontal scrolling | Yes | — |
 | [`snapshot_policy`](#snapshot_policy) | When to write the web preview frame | No, core-internal | n/a |
 | [`sports_card`](#sports_card) | Scoreboard card settings, colours, fonts, dates | Yes (scoreboards) | 3.3.0 |
+| [`sports_card_wrappers`](#sports_card_wrappers) | The game renderer's `sports_card` delegations | Yes (scoreboards) | Unreleased |
+| [`sports_celebration`](#sports_celebration) | Draw a scoreboard's score/win celebration | Yes (scoreboards) | Unreleased |
+| [`sports_fetch`](#sports_fetch) | Scoreboard season fetch, lookback and live-odds decisions | Yes (scoreboards) | Unreleased |
 | [`sports_game_renderer`](#sports_game_renderer) | Scoreboard scroll/Vegas card geometry | Yes (scoreboards) | 3.3.0 |
 | [`sports_helpers`](#sports_helpers) | Small helpers every scoreboard `sports.py` copies | Yes (scoreboards) | 3.5.0 |
 | [`sports_scroll`](#sports_scroll) | Scoreboard scroll-display orchestration | Yes (scoreboards) | 3.2.0 |
@@ -46,7 +49,7 @@ Rules for the package:
 | [`sync_manager`](#sync_manager) | Leader/follower sync between two displays | No, core-internal | n/a |
 | [`text_helper`](#text_helper) | Outlined text, wrapping, measurement | Yes | — |
 
-The four `sports_*` mixin and card modules hold code the scoreboard plugins
+The `sports_*` mixin and card modules hold code the scoreboard plugins
 used to carry as identical copies. Each module docstring lists what a host
 class must provide. The plan behind them is in
 [docs/SPORTS_UNIFICATION.md](../../docs/SPORTS_UNIFICATION.md).
@@ -216,6 +219,33 @@ dates (`format_game_date()`, `format_game_time()`, `card_tzinfo()`) and font
 sizes (`schema_font_size()`, `resolve_font_size()`). A plugin keeps its own
 method and delegates the body.
 
+### sports_card_wrappers
+
+[`sports_card_wrappers.py`](sports_card_wrappers.py).
+`SportsCardWrappersMixin`: the one-line methods a scoreboard's game renderer
+uses to call `sports_card` with its own `config` and `logger`
+(`_vs_text()`, `_element_color()`, `_format_game_date()`, ... seventeen in
+all), under their existing names. They are what `sports_game_renderer`'s
+mixin expects its host to provide. No `__init__` and no state.
+
+### sports_celebration
+
+[`sports_celebration.py`](sports_celebration.py). `SportsCelebrationMixin`
+draws the full-screen takeover a scoreboard shows when a team scores or wins
+(`_draw_celebration_layout(celebration)`): a backdrop in the scoring team's
+colours read off its crest, scenery, confetti, the headline and the score.
+The colour helpers are free functions (`logo_palette()`, `lift_color()`,
+`mix_color()`, ...). Deciding *when* to celebrate stays in the plugin, which
+builds the celebration dict the docstring describes.
+
+### sports_fetch
+
+[`sports_fetch.py`](sports_fetch.py). `SportsFetchMixin`: the `SportsCore`
+methods that decide which requests a scoreboard makes --
+`_fetch_season_directly()` (a season, in chunks ESPN accepts),
+`_background_fetches_espn_ranges()`, `_needs_previous_day()` (the live
+lookback) and `_wants_live_odds()` (odds only for games near the screen).
+
 ### sports_game_renderer
 
 [`sports_game_renderer.py`](sports_game_renderer.py).