chore: remove dead code, deprecate unused plugin APIs (over-engineering audit) (#783)

* chore: remove dead code, deprecate unused plugin APIs (over-engineering audit)

Whole-tree audit. Every symbol was checked against core, the plugin
monorepo and all eight third-party plugins in plugins.json first.

- Deprecate (removal 3.10.0) plugin-facing methods nothing calls:
  LogoDownloader bulk download, ConfigManager backup/secret wrappers,
  APIHelper extras, BackgroundDataService poll API, PluginManager /
  PluginStateManager info readers, and a few CacheManager, FontManager,
  BaseOddsManager, DynamicTeamResolver methods and PluginTestCase.
  plugin_api_usage.py learns their receiver names; DEPRECATIONS doc
  regenerated.
- Remove core-internal dead code: CacheMetrics, Vegas status/stats
  plumbing, sync "new cycle" message (followers ignore unknown types),
  unused operation types, test-only PluginCatalog readers, IPC to_dict
  and ping, _parse_form_value, CacheStrategyProtocol, ErrorAggregator
  callbacks, duplicate web response helpers.
- Web UI: drop never-mounted json-file-manager.js, the example widget,
  utils/error_handler.js, four uncalled PluginAPI methods, and 29
  escapeHtml shims (call window.LEDEscape directly). Public globals,
  BaseWidget and widget names unchanged.
- Remove six one-off scripts (owner decision) and the unused markupsafe
  and pytest-mock pins.

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

* fix(web): calendar picker error text goes in a text node, not innerHTML

Same output as the escaped innerHTML it replaces; clears Codacy's
XSS-pattern alerts on the line.

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

---------

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

src/plugin_system/state_reconciliation.py

@@ -38,7 +38,6 @@ class InconsistencyType(Enum):
     PLUGIN_MISSING_ON_DISK = "plugin_missing_on_disk"
     PLUGIN_ENABLED_MISMATCH = "plugin_enabled_mismatch"
     PLUGIN_VERSION_MISMATCH = "plugin_version_mismatch"
-    PLUGIN_STATE_CORRUPTED = "plugin_state_corrupted"
 
 
 class FixAction(Enum):
@@ -57,7 +56,6 @@ class Inconsistency:
     fix_action: FixAction
     current_state: Dict[str, Any]
     expected_state: Dict[str, Any]
-    can_auto_fix: bool = False
 
 
 @dataclass
@@ -270,7 +268,7 @@ class StateReconciliation:
 
             # Attempt to fix auto-fixable inconsistencies
             for inconsistency in inconsistencies:
-                if inconsistency.can_auto_fix and inconsistency.fix_action == FixAction.AUTO_FIX:
+                if inconsistency.fix_action == FixAction.AUTO_FIX:
                     if self._fix_inconsistency(inconsistency):
                         fixed.append(inconsistency)
                     else:
@@ -428,7 +426,6 @@ class StateReconciliation:
                 fix_action=FixAction.AUTO_FIX,
                 current_state={'exists_in_config': False},
                 expected_state={'exists_in_config': True, 'enabled': False},
-                can_auto_fix=True
             ))
         
         # Check: Plugin in config but not on disk
@@ -459,7 +456,6 @@ class StateReconciliation:
                 fix_action=FixAction.AUTO_FIX if can_repair else FixAction.MANUAL_FIX_REQUIRED,
                 current_state={'exists_on_disk': False},
                 expected_state={'exists_on_disk': True},
-                can_auto_fix=can_repair
             ))
         
         # Observed checks: only against a live snapshot, and only for a plugin
@@ -486,7 +482,6 @@ class StateReconciliation:
                     fix_action=FixAction.NO_ACTION,
                     current_state={'loaded': loaded, 'state': runtime.get('state')},
                     expected_state={'loaded': config_enabled},
-                    can_auto_fix=False
                 ))
             loaded_version = runtime.get('loaded_version')
             disk_version = disk.get('version')
@@ -500,7 +495,6 @@ class StateReconciliation:
                     fix_action=FixAction.NO_ACTION,
                     current_state={'version': loaded_version},
                     expected_state={'version': disk_version},
-                    can_auto_fix=False
                 ))
 
         return inconsistencies