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>

test/test_error_handling.py

@@ -31,3 +31,18 @@ class TestCustomExceptions:
         # DisplayError includes context in string representation
         assert "Display not found" in str(error)
         assert error.context.get('display_mode') == 'adafruit'
+
+    def test_callers_context_dict_is_not_mutated(self):
+        """A caller reusing one context dict across raises used to have
+        every error's own key written into it."""
+        cases = [
+            (CacheError, {'cache_key': 'k'}),
+            (ConfigError, {'config_path': 'c.json', 'field': 'f'}),
+            (PluginError, {'plugin_id': 'weather'}),
+            (DisplayError, {'display_mode': 'm'}),
+        ]
+        for cls, kwargs in cases:
+            shared = {'attempt': 1}
+            error = cls("boom", context=shared, **kwargs)
+            assert shared == {'attempt': 1}, cls.__name__
+            assert error.context == {'attempt': 1, **kwargs}, cls.__name__