feat(scroll): upstream the scroll orchestration layer; release 3.2.0

Phases B3 and B4.

B3 -- src/common/sports_scroll.py is deliberately NOT a superset of the
ten plugin scroll_display.py copies. A method-level comparison of the
eight that share a shape (f1 and ufc are genuine forks) found a sharp
split, and the module is drawn along it:

  promoted   orchestration -- get_all_vegas_content_items is identical
             in all eight; clear_all, get_scroll_info,
             get_dynamic_duration, is_complete and display_frame are
             96-100% similar
  promoted   settings -- one algorithm; the copies differ only in which
             league keys they walk, so the ladder is data
             (SCROLL_LEAGUE_KEYS) rather than a body per sport
  NOT        content -- prepare_scroll_content has 8 distinct bodies
             across 8 plugins (145 lines, 53% similar at worst) and
             _load_separator_icons 7 (6% at worst)

Same name, different job: prepare_scroll_content draws *this sport's*
game card. Merging those eight bodies would be exactly the mistake the
promotion rule exists to prevent, so the base raises NotImplementedError
rather than rendering something plausible -- a base that rendered
something would let a plugin ship a silently blank scroll.

The one behavior added over the plugin copies is native
global_config['target_fps'] support. The bundled copies hardcode ~100
FPS via scroll_delay and never consult the global target; Part A
threaded it through each copy by hand, and this makes that threading
legacy compatibility rather than the mechanism.

66 tests, including three against the real ScrollHelper rather than a
double -- a suite built entirely on MagicMock would sail straight past a
rename in the helper.

B4 -- bump src/__init__.py to 3.2.0 and close the CHANGELOG's Unreleased
section against it. This is the number the sunset rule keys on: the
first core release shipping the unified sports library, and therefore
the floor a plugin sets ledmatrix_min_version to before deleting its
bundled copies. The version bump and the changelog release heading move
together on purpose -- separating them would leave a commit whose
changelog announces 3.2.0 while the code still reports 3.1.0.

Nothing here changes what an existing plugin loads; adoption is B5.

Gates: 714 core unit, 66 plugin safety.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FgbA8SMutQQpXkMG8LMmC4

.github/workflows/test.yml

@@ -75,4 +75,5 @@ jobs:
             test/test_element_style.py \
             test/test_sports_core_promotions.py \
             test/test_sports_modes_promotions.py \
-            test/test_sports_capabilities.py
+            test/test_sports_capabilities.py \
+            test/test_sports_scroll.py