fix(core): font zip cache, monotonic timers, resolver back-off, and other core/common fixes (#654)

* fix(core): font zip cache, monotonic timers, resolver back-off, and other core/common fixes

- font_manager: a .zip font URL is served as its extracted font after a
  restart (the cached-file check returned the archive first); downloads
  use requests with a 30s timeout into a temp file + os.replace.
- api_helper / sync_manager: rate-limit and heartbeat/leader timeouts use
  time.monotonic(); last_request_time and the status file's ts stay
  wall-clock. set_on_new_cycle docstring no longer claims core uses it.
- logo_helper: the placeholder uses the same scaled box as a real logo.
- permission_utils: one _sudo_bash_candidates() helper (with the sudoers
  exact-argv rationale) shared by sudo_remove_directory, which now retries
  the next bash path on a sudo refusal, and install_requirements_file.
- dynamic_team_resolver: failed/empty fetch backs off 5 min; duplicate
  INFO log and contradictory docstring example fixed.
- element_style: scale default looked up through element aliases.
- background_data_service: cache-hit callback runs outside the lock.
- config_arrays: union-aware type check (["array","null"]); stale
  dotToNested() reference removed.
- auto_update_setup: non-dict auto_update reads as off; temp result file
  unlinked when the write fails.
- exceptions: constructors copy the caller's context dict.
- logging_config: StructuredFormatter json.dumps(default=str).
- error_aggregator: removed unused export_path/export_to_file/_auto_export.
- Docstrings: validate_file_upload max_size_mb, raise_on_errors.

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

* fix(sync): retry the status-file rename like the other atomic writers

On Windows os.replace can fail with "Access is denied" while a scanner
briefly holds the target open; config_manager_atomic._replace already
retries that (and re-raises at once on other platforms). The sync status
writer called os.replace directly, which made
test_concurrent_writers_each_use_their_own_temp_file flaky on Windows.

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

---------

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

src/exceptions.py

@@ -42,7 +42,9 @@ class CacheError(LEDMatrixError):
             context: Optional context dictionary
         """
         if cache_key:
-            context = context or {}
+            # Copy so the caller's dict isn't mutated (a reused context
+            # dict would otherwise collect every error's keys).
+            context = dict(context or {})
             context['cache_key'] = cache_key
         super().__init__(message, context)
         self.cache_key = cache_key
@@ -62,7 +64,9 @@ class ConfigError(LEDMatrixError):
             context: Optional context dictionary
         """
         if config_path or field:
-            context = context or {}
+            # Copy so the caller's dict isn't mutated (a reused context
+            # dict would otherwise collect every error's keys).
+            context = dict(context or {})
             if config_path:
                 context['config_path'] = config_path
             if field:
@@ -85,7 +89,9 @@ class PluginError(LEDMatrixError):
             context: Optional context dictionary
         """
         if plugin_id:
-            context = context or {}
+            # Copy so the caller's dict isn't mutated (a reused context
+            # dict would otherwise collect every error's keys).
+            context = dict(context or {})
             context['plugin_id'] = plugin_id
         super().__init__(message, context)
         self.plugin_id = plugin_id
@@ -104,7 +110,9 @@ class DisplayError(LEDMatrixError):
             context: Optional context dictionary
         """
         if display_mode:
-            context = context or {}
+            # Copy so the caller's dict isn't mutated (a reused context
+            # dict would otherwise collect every error's keys).
+            context = dict(context or {})
             context['display_mode'] = display_mode
         super().__init__(message, context)
         self.display_mode = display_mode