multi-user: users, per-user profiles/filters/notifications, tab UI, apply forensics

* DB: users + user_profiles/filters/notifications/preferences; applications gets
  user_id + forensics_json + profile_snapshot_json; new errors table
  with 14d retention; schema versioning via MIGRATIONS list
* auth: password hashes in DB (argon2); env vars seed first admin; per-user
  sessions; CSRF bound to user id
* apply: personal info/WBS moved out of env into the request body; providers
  take an ApplyContext with Profile + submit_forms; full Playwright recorder
  (step log, console, page errors, network, screenshots, final HTML)
* web: five top-level tabs (Wohnungen/Bewerbungen/Logs/Fehler/Einstellungen);
  settings sub-tabs profil/filter/benachrichtigungen/account/benutzer;
  per-user matching, auto-apply and notifications (UI/Telegram/SMTP); red
  auto-apply switch on Wohnungen tab; forensics detail view for bewerbungen
  and fehler; retention background thread

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

apply/providers/_provider.py

@@ -1,22 +1,37 @@
+"""Abstract provider interface. Concrete providers live next to this file."""
 import asyncio
-from abc import ABC, abstractmethod
 import logging
+from abc import ABC, abstractmethod
+from dataclasses import dataclass
 
+from actions import Recorder
 from classes.application_result import ApplicationResult
+from classes.profile import Profile
 
 logger = logging.getLogger("flat-apply")
 
+
+@dataclass
+class ApplyContext:
+    """Per-request state passed into every provider call."""
+    profile: Profile
+    submit_forms: bool
+    recorder: Recorder
+
+
 class Provider(ABC):
     @property
     @abstractmethod
     def domain(self) -> str:
-        """every flat provider needs a domain"""
-        pass
+        ...
 
     @abstractmethod
-    async def apply_for_flat(self, url: str) -> ApplicationResult:
-        """every flat provider needs to be able to apply for flats"""
-        pass
+    async def apply_for_flat(self, url: str, ctx: ApplyContext) -> ApplicationResult:
+        ...
 
-    def test_apply(self, url):
-        print(asyncio.run(self.apply_for_flat(url)))
+    def test_apply(self, url, profile: Profile | None = None, submit_forms: bool = False):
+        rec = Recorder(url)
+        ctx = ApplyContext(profile or Profile(), submit_forms=submit_forms, recorder=rec)
+        result = asyncio.run(self.apply_for_flat(url, ctx))
+        print(repr(result))
+        return result, rec.to_json()