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/common/api_helper.py

@@ -84,7 +84,11 @@ class APIHelper:
         self.session.headers.update({**DEFAULT_HTTP_HEADERS, 'Connection': 'keep-alive'})
         
         # Rate limiting
-        self._last_request_time = 0
+        self._last_request_time = 0  # wall clock, reported by get_request_stats()
+        # The interval is measured on time.monotonic(): a wall-clock step
+        # back (NTP correcting a Pi with no RTC) made time_since_last
+        # negative and the "remaining interval" sleep as long as the step.
+        self._last_request_monotonic: Optional[float] = None
         self._min_request_interval = 1.0  # Minimum seconds between requests
     
     def get(self, url: str, params: Optional[Dict] = None, 
@@ -333,13 +337,14 @@ class APIHelper:
     
     def _enforce_rate_limit(self) -> None:
         """Enforce rate limiting between requests."""
-        current_time = time.time()
-        time_since_last = current_time - self._last_request_time
-        
-        if time_since_last < self._min_request_interval:
-            sleep_time = self._min_request_interval - time_since_last
-            time.sleep(sleep_time)
-        
+        if self._last_request_monotonic is not None:
+            time_since_last = time.monotonic() - self._last_request_monotonic
+
+            if time_since_last < self._min_request_interval:
+                sleep_time = self._min_request_interval - time_since_last
+                time.sleep(sleep_time)
+
+        self._last_request_monotonic = time.monotonic()
         self._last_request_time = time.time()
     
     def set_rate_limit(self, min_interval: float) -> None:
@@ -362,5 +367,8 @@ class APIHelper:
         return {
             'min_request_interval': self._min_request_interval,
             'last_request_time': self._last_request_time,
-            'time_since_last_request': time.time() - self._last_request_time
+            'time_since_last_request': (
+                time.monotonic() - self._last_request_monotonic
+                if self._last_request_monotonic is not None
+                else time.time() - self._last_request_time),
         }