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/startup_validator.py

@@ -318,12 +318,21 @@ class StartupValidator:
     
     def raise_on_errors(self) -> None:
         """
-        Raise exceptions if validation errors exist.
-        
+        Raise one exception if validation errors exist; return None if not.
+
+        Nothing in core calls this (see the module docstring). Errors are
+        grouped by a keyword in their message, not by which check produced
+        them, and only the first non-empty group is raised, in the order
+        config > cache > plugin: a "plugin ... config" message counts as a
+        config error, and cache/plugin errors are not reported while a
+        config error exists. The raised exception's ``context['errors']``
+        holds that group's messages only.
+
         Raises:
-            ConfigError: If configuration validation fails
-            CacheError: If cache validation fails
-            PluginError: If plugin validation fails
+            ConfigError: If any message mentions config/configuration, or if
+                none matches any group
+            CacheError: If a message mentions cache (and none config)
+            PluginError: If a message mentions plugin (and none of the above)
         """
         if not self.errors:
             return