chore(deprecation): remove the 35 APIs deprecated for 3.8.0 (#708)

* chore(deprecation): remove the 35 APIs deprecated for 3.8.0

The usage scan (docs/DEPRECATIONS_3.8.md, regenerated 2026-10-01 and
committed here) finds no call or override of any of them in the 46
monorepo plugins or the 8 third-party plugins plugins.json lists; the
only core callers were other deprecated methods removed alongside.

- CacheManager: 13 methods, plus the private helpers only
  has_data_changed used (_has_*_changed, _is_market_open).
- DisplayManager: 7 methods, plus WEATHER_COLORS and the private
  _draw_sun/_cloud/_rain/_snow/_storm helpers only the icon methods used.
- FontManager: 14 methods, plus size_tokens, _save_overrides and
  _clear_plugin_font_cache. font_overrides and _load_overrides stay:
  resolve_font() still applies config/font_overrides.json.
  performance_stats stays: get_font() keeps it and tests read it.
- PluginManager.get_enabled_plugins.

test_deprecation.py pins only the two 3.9.0 markers now; the scanner
tests run against a stand-in core instead of the real markers. The
memory-tier tests read stats through log_memory_cache_stats() and the
component, and the test of the removed _clear_plugin_font_cache goes.
Docs drop the removed methods' reference entries; the Deprecated APIs
table becomes "Removed in 3.8.0". CHANGELOG gains a Removed section.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* chore(deprecation): drop the test harness's copies of the removed icon methods

VisualTestDisplayManager still drew weather icons that DisplayManager no
longer has, so a plugin's visual tests could pass on calls that raise
AttributeError on the real display. Its draw_sun/draw_cloud/draw_rain/
draw_snow/draw_weather_icon/draw_text_with_icons, WEATHER_COLORS and the
private helpers go, with the tests that exercised them. The CHANGELOG's
Deprecations entries no longer say nothing is removed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

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

CHANGELOG.md

@@ -538,18 +538,52 @@ read any of them:
 - The 35 plugin-facing methods deprecated in 3.5.0 are now removed in 3.8.0,
   not 3.7.0: 3.7.0 shipped with all of them still in place, still warning
   "will be removed in LEDMatrix 3.7.0". The warning, the docs and
-  `test/test_deprecation.py` now say 3.8.0. Nothing is removed yet.
+  `test/test_deprecation.py` now say 3.8.0. They are removed in this
+  release (see Removed, below).
 - New `scripts/plugin_api_usage.py` lists every `@deprecated` core method and
   scans core, the plugin monorepo and the registry's third-party plugins for
   calls and overrides, telling real uses from unrelated methods of the same
   name. Its output is `docs/DEPRECATIONS_3.8.md` (linked from
-  `docs/PLUGIN_API_REFERENCE.md#deprecated-apis`): 34 of the 35 are unused;
-  `CacheManager.get_memory_cache_stats` is still called by core's own
-  `log_memory_cache_stats()`, so it stays until that call migrates.
+  `docs/PLUGIN_API_REFERENCE.md#deprecated-apis`); no plugin uses any of
+  the 35.
 - `test/test_deprecation.py` fails while any `@deprecated` marker names a
   release at or below `src.__version__`, so a release can no longer ship
   warning about a removal it has already passed.
 
+### Removed
+
+The 35 plugin-facing methods deprecated in 3.5.0 (each has logged a warning
+on first call since, announced for 3.7.0 and then moved to 3.8.0) are gone.
+The usage scan (`docs/DEPRECATIONS_3.8.md`, re-run 2026-10-01) found no call
+or override of any of them in the 46 monorepo plugins or the 8 third-party
+plugins `plugins.json` lists, and core's own last callers went with them. A
+plugin that still calls one gets an `AttributeError`;
+`docs/PLUGIN_API_REFERENCE.md#deprecated-apis` lists what to use instead.
+
+- `CacheManager`: `has_data_changed`, `update_cache`, `setup_persistent_cache`,
+  `get_sport_live_interval`, `get_sport_key_from_cache_key`,
+  `get_background_cached_data`, `is_background_data_available`,
+  `record_cache_hit`, `record_cache_miss`, `record_fetch_time`,
+  `get_cache_metrics`, `log_cache_metrics`, `get_memory_cache_stats`. The
+  private change-detection helpers behind `has_data_changed`
+  (`_has_weather_changed` and friends, `_is_market_open`) went with it.
+- `DisplayManager`: `draw_weather_icon`, `draw_sun`, `draw_cloud`, `draw_rain`,
+  `draw_snow`, `draw_text_with_icons`, `get_scrolling_stats`, and with them
+  the `WEATHER_COLORS` table and the private `_draw_sun`/`_draw_cloud`/
+  `_draw_rain`/`_draw_snow`/`_draw_storm` helpers.
+  `VisualTestDisplayManager` (the plugin test harness) drops its copies of
+  the icon methods too, so a plugin's visual tests fail the way the real
+  display would instead of passing against methods that no longer exist.
+- `FontManager`: `set_override`, `remove_override`, `get_overrides`,
+  `add_font`, `remove_font`, `validate_font`, `get_font_catalog`,
+  `get_available_fonts`, `get_size_tokens`, `get_performance_stats`,
+  `get_manager_fonts`, `get_detected_fonts`, `get_plugin_fonts`,
+  `unregister_plugin_fonts`, plus the `size_tokens` attribute and the private
+  `_save_overrides` and `_clear_plugin_font_cache`. `resolve_font()` still
+  applies `config/font_overrides.json`.
+- `PluginManager.get_enabled_plugins` (check `enabled` on the entries in
+  `plugin_manager.plugins`).
+
 ### Web UI styling: a real Tailwind build
 
 - The web UI's utility classes now come from a generated