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_auto_update_setup.py

@@ -75,6 +75,25 @@ def test_does_nothing_while_updates_are_off(tmp_path):
     assert not (root / aus.RESULT_REL).exists()
 
 
+@pytest.mark.parametrize('value', [True, 'yes', ['enabled']])
+def test_a_non_object_auto_update_value_reads_as_off(value):
+    """A hand-edited "auto_update": true raised AttributeError and aborted
+    setup; the web UI's save treats a non-object as {} (off), so this does too."""
+    assert aus.is_enabled({'auto_update': value}) is False
+
+
+def test_a_failed_result_write_leaves_no_temp_file(tmp_path, monkeypatch):
+    root, etc = project(tmp_path)
+
+    def broken_dump(*args, **kwargs):
+        raise OSError('disk full')
+    monkeypatch.setattr(aus.json, 'dump', broken_dump)
+    setup(root, etc, FakeSystemctl())._report('failed', 'x')
+    leftovers = [p.name for p in (root / aus.RESULT_REL).parent.iterdir()
+                 if p.name.startswith('.auto_update_setup_')]
+    assert leftovers == []
+
+
 def test_installs_both_units_for_the_web_user(tmp_path):
     root, etc = project(tmp_path)
     systemctl = FakeSystemctl()