chore(deps): remove packages nothing imports, declare direct imports, move mypy to test deps

Removed from requirements.txt: python-socketio, python-engineio,
websockets, websocket-client — zero imports anywhere in this repo, and
the one store plugin that needs Socket.IO (ledmatrix-music) declares it
in its own requirements.txt, which the plugin store installs. Removed
the same quartet plus timezonefinder, geopy, google-auth-oauthlib,
google-auth-httplib2, google-api-python-client, unidecode, icalevents,
python-dateutil, flask-wtf and the werkzeug pin from
web_interface/requirements.txt — all leftovers from the deleted built-in
weather/calendar/music displays (flask-wtf was doubly dead: app.py
explicitly disables CSRF and sets csrf=None). scripts/
install_dependencies_apt.py, which mirrors these lists for the
first-time installer, drops the same packages.

Added: urllib3 (imported directly in four core modules), jinja2 and
markupsafe (imported directly in pages_v3.py) — previously reachable
only as transitives. mypy moves from runtime requirements to
requirements-test.txt.

Verified in a fresh venv: all four requirements files co-install, pip
check is clean, the full CI-enrolled suite (907 tests) and a Flask boot
smoke pass with the trimmed dependency set.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SXb4mKcAkVaxkeTb3YnAdr

requirements.txt

@@ -11,27 +11,22 @@ pytz>=2024.2,<2025.0  # Updated for latest timezone data
 
 # HTTP requests
 requests>=2.33.0,<3.0.0
+urllib3>=1.26.0,<3.0.0  # requests transitive, but imported directly (urllib3.util.retry.Retry)
 
 # Google API integration
 
 # Font rendering
 freetype-py>=2.5.1,<3.0.0
 
-# Spotify integration
+# Spotify integration (used by web_interface/blueprints/api_v3.py OAuth endpoints)
 spotipy>=2.25.2,<3.0.0
 
 # Flask web framework
 Flask>=3.1.3,<4.0.0
 
-# Text processing
-
-# Calendar integration
-
-# WebSocket support
-python-socketio>=5.14.0,<6.0.0
-python-engineio>=4.9.0,<5.0.0
-websockets>=12.0,<14.0
-websocket-client>=1.8.0,<2.0.0
+# WebSocket support: intentionally NOT declared here. Plugins that need
+# it (e.g. ledmatrix-music's Socket.IO client) declare it in their own
+# requirements.txt, which the plugin store installs.
 
 # JSON Schema validation
 jsonschema>=4.20.0,<5.0.0
@@ -43,7 +38,6 @@ packaging>=23.0,<27.0
 pytest>=9.0.3,<10.0.0
 pytest-cov>=4.1.0,<5.0.0
 pytest-mock>=3.11.0,<4.0.0
-mypy>=1.5.0,<2.0.0
 
 # ───────────────────────────────────────────────────────────────────────
 # Optional dependencies — the code imports these inside try/except