chore: sweep dead code across all three services

Per review §1 — verified no callers before each deletion:

- _next_scrape_utc (context dict key never read by any template)
- ALERT_SCRAPE_INTERVAL_SECONDS settings import (only _next_scrape_utc read it)
- alert/paths.py (imported by nothing)
- alert/settings.py LANGUAGE (alert doesn't use translations.toml)
- alert/main.py: the vestigial `c = {}` connectivity dict, the comment
  about re-enabling it, and the entire connectivity block in
  _flat_payload — the web-side columns stay NULL on insert now
- alert/maps.py: DESTINATIONS, calculate_score, _get_next_weekday,
  _calculate_transfers (only geocode is used in the scraper)
- alert/flat.py: connectivity + display_address properties,
  _connectivity field, unused datetime import
- apply/utils.py str_to_preview (no callers) — file removed
- web/matching.py: max_morning_commute + commute check
- web/app.py: don't pass connectivity dict into flat_matches_filter,
  don't write email_address through update_notifications
- web/db.py: get_error (no callers); drop kill_switch,
  max_morning_commute, email_address from their allowed-sets so they're
  not writable through update_* anymore
- web/settings.py + docker-compose.yml: SMTP_HOST/PORT/USERNAME/PASSWORD/
  FROM/STARTTLS (notifications.py is telegram-only now)

DB columns themselves (kill_switch, email_address, max_morning_commute,
connectivity_morning_time, connectivity_night_time) stay in the schema
— SQLite can't drop them cheaply and they're harmless.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/db.py

@@ -435,7 +435,7 @@ def get_filters(user_id: int) -> sqlite3.Row:
 def update_filters(user_id: int, data: dict) -> None:
     _ensure_user_rows(user_id)
     allowed = {"rooms_min", "rooms_max", "max_rent", "min_size",
-               "max_morning_commute", "wbs_required", "max_age_hours"}
+               "wbs_required", "max_age_hours"}
     clean = {k: data.get(k) for k in allowed if k in data}
     if not clean:
         return
@@ -453,7 +453,7 @@ def get_notifications(user_id: int) -> sqlite3.Row:
 def update_notifications(user_id: int, data: dict) -> None:
     _ensure_user_rows(user_id)
     allowed = {
-        "channel", "telegram_bot_token", "telegram_chat_id", "email_address",
+        "channel", "telegram_bot_token", "telegram_chat_id",
         "notify_on_match", "notify_on_apply_success", "notify_on_apply_fail",
     }
     clean = {k: v for k, v in data.items() if k in allowed}
@@ -473,7 +473,7 @@ def get_preferences(user_id: int) -> sqlite3.Row:
 def update_preferences(user_id: int, data: dict) -> None:
     _ensure_user_rows(user_id)
     allowed = {
-        "auto_apply_enabled", "submit_forms", "kill_switch",
+        "auto_apply_enabled", "submit_forms",
         "apply_circuit_open", "apply_recent_failures",
     }
     clean = {k: v for k, v in data.items() if k in allowed}
@@ -719,10 +719,6 @@ def recent_errors(user_id: Optional[int], limit: int = 100,
     ).fetchall())
 
 
-def get_error(error_id: int) -> Optional[sqlite3.Row]:
-    return _get_conn().execute("SELECT * FROM errors WHERE id = ?", (error_id,)).fetchone()
-
-
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