fix: address PR review findings

Fix (10 of 15 findings):

plugin-repos/march-madness/requirements.txt:
  Add urllib3>=1.26.0 — manager.py directly imports from urllib3; it was
  an undeclared transitive dependency via requests.

scripts/dev/dev_plugin_setup.sh:
  Restore subshell form (cd "$target_dir" && git pull --rebase) || true
  so the shell's working directory is not permanently changed after the
  if-cd block. Previous fix for SC2015 leaked cwd into the remainder of
  the script.

src/base_classes/sports.py:
  Narrow 'except Exception' to 'except RuntimeError as e' and log via
  self.logger.debug — Path.home() raises only RuntimeError for service
  users; other exceptions should not be silently swallowed.

src/config_service.py:
  Fix stale "MD5 checksum" in ConfigVersion.__init__ docstring (line 40);
  the implementation uses SHA-256 since the Codacy fix.

src/wifi_manager.py:
  Log the last-resort AP enable failure with exc_info=True instead of
  silently passing — failure here means the device may be unreachable.

web_interface/blueprints/pages_v3.py:
  Log the outer metadata pre-load exception at debug level instead of
  swallowing it silently; schema still loads fully below.

src/background_data_service.py:
  Remove unused 'timeout' parameter from shutdown() — executor.shutdown()
  does not accept timeout; update __del__ caller accordingly.

src/font_manager.py:
  Validate URL scheme before urlretrieve — reject non-http/https schemes
  (e.g. file://) to prevent reading local files from config-supplied URLs.

src/plugin_system/plugin_executor.py:
  Simplify redundant except tuple: (PluginTimeoutError, PluginError,
  Exception) → Exception, which already covers the others.

test/test_display_controller.py:
  Mark empty test_plugin_discovery_and_loading as @pytest.mark.skip with
  reason. Move duplicate 'from datetime import datetime' to module header
  and remove the stray mid-module copy.

Skip (5 of 15 findings, with reasons):
  - pytest 9.0.3 concerns: full suite already verified (467 pass, 18 pre-existing)
  - Pillow 12.2.0 API concerns: no deprecated APIs in codebase; tests + Pi smoke test pass
  - diagnose_web_ui.sh sudo validation: set -e already ensures fail-fast on any sudo failure
  - app.py request-logging except: must stay silent (recursive logging risk); annotated
  - app.py SSE file-read except: genuinely transient I/O; annotated

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/font_manager.py

@@ -3,6 +3,7 @@ import logging
 import freetype
 import json
 import hashlib
+import urllib.parse
 import urllib.request
 import zipfile
 import tempfile
@@ -265,9 +266,12 @@ class FontManager:
                 logger.info(f"Using cached font: {cache_path}")
                 return str(cache_path)
 
-            # Download font
+            # Download font — restrict to http/https to prevent file:// reads
+            parsed = urllib.parse.urlparse(url)
+            if parsed.scheme not in ('http', 'https'):
+                raise ValueError(f"Font URL must use http or https, got: {parsed.scheme!r}")
             logger.info(f"Downloading font from {url}")
-            urllib.request.urlretrieve(url, cache_path)  # nosec B310 - URL from user's own config file on local device
+            urllib.request.urlretrieve(url, cache_path)  # nosec B310 - scheme validated above
 
             # Handle zip files
             if url.endswith('.zip'):