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>

src/plugin_system/plugin_manager.py

@@ -32,7 +32,6 @@ from src.plugin_system.schema_manager import (
 from src.plugin_system.plugin_dirs import (
     ManifestStatus, PluginDirectoryIndex, resolve_plugin_dir,
 )
-from src.deprecation import deprecated
 from src.common.permission_utils import (
     ensure_directory_permissions,
     get_plugin_dir_mode
@@ -873,16 +872,6 @@ class PluginManager:
         """
         return self.plugins.copy()
     
-    @deprecated("3.8.0", "check each plugin's enabled flag in plugins")
-    def get_enabled_plugins(self) -> List[str]:
-        """
-        Get list of enabled plugin IDs.
-        
-        Returns:
-            List of plugin IDs that are currently enabled
-        """
-        return [pid for pid, plugin in self.plugins.items() if plugin.enabled]
-    
     def get_plugin_info(self, plugin_id: str) -> Optional[Dict[str, Any]]:
         """
         Get information about a plugin (manifest + runtime info).