Refactor cron to call API via HTTP, capture base_url from browser

- meal-cron now runs send_reminders_cron.sh (simple wget loop, no DB mount)
- New /api/cron-tick endpoint handles all timezone logic server-side
- base_url captured from request.host_url when user saves ntfy settings,
  stored per-user — no APP_BASE_URL env var needed
- Cron endpoint protected by CRON_SECRET shared env var
- Removed send_reminders_cron.py, DB volume from cron container
- tests: 3 new cron-tick + base_url capture tests (69 total)

models.py

@@ -75,6 +75,8 @@ def init_db() -> None:
             db.execute("ALTER TABLE users ADD COLUMN ntfy_token TEXT DEFAULT ''")
         if "callback_token" not in cols:
             db.execute("ALTER TABLE users ADD COLUMN callback_token TEXT DEFAULT ''")
+        if "base_url" not in cols:
+            db.execute("ALTER TABLE users ADD COLUMN base_url TEXT DEFAULT ''")
 
         # Migration: add timezone and reminder tracking to households
         hh_cols = [r["name"] for r in db.execute("PRAGMA table_info(households)").fetchall()]
@@ -207,13 +209,13 @@ def get_household_users(household_id: int) -> list[dict]:
 # ── Ntfy / notifications ─────────────────────────────────────────────────────
 
 def set_user_ntfy(user_id: int, ntfy_url: str, ntfy_token: str,
-                  callback_token: str) -> None:
+                  callback_token: str, base_url: str = "") -> None:
     """Save ntfy settings for a user."""
     with get_db() as db:
         db.execute(
-            "UPDATE users SET ntfy_url = ?, ntfy_token = ?, callback_token = ? "
-            "WHERE id = ?",
-            (ntfy_url, ntfy_token, callback_token, user_id),
+            "UPDATE users SET ntfy_url = ?, ntfy_token = ?, callback_token = ?, "
+            "base_url = ? WHERE id = ?",
+            (ntfy_url, ntfy_token, callback_token, base_url, user_id),
         )
 
 
@@ -221,7 +223,7 @@ def get_user_ntfy(user_id: int) -> dict:
     """Get ntfy settings for a user."""
     with get_db() as db:
         row = db.execute(
-            "SELECT ntfy_url, ntfy_token, callback_token FROM users WHERE id = ?",
+            "SELECT ntfy_url, ntfy_token, callback_token, base_url FROM users WHERE id = ?",
             (user_id,),
         ).fetchone()
         return dict(row) if row else {}
@@ -241,7 +243,7 @@ def get_users_with_ntfy(household_id: int) -> list[dict]:
     """Return all users in a household who have ntfy configured."""
     with get_db() as db:
         rows = db.execute(
-            "SELECT id, username, ntfy_url, ntfy_token, callback_token "
+            "SELECT id, username, ntfy_url, ntfy_token, callback_token, base_url "
             "FROM users WHERE household_id = ? "
             "AND ntfy_url != '' AND callback_token != '' "
             "ORDER BY username",