enrichment: Haiku flat details + image gallery on expand

apply service
- POST /internal/fetch-listing: headless Playwright fetch of a listing URL,
  returns {html, image_urls[], final_url}. Uses the same browser
  fingerprint/profile as the apply run so bot guards don't kick in

web service
- New enrichment pipeline (web/enrichment.py):
  /internal/flats → upsert → kick() enrichment in a background thread
    1. POST /internal/fetch-listing on apply
    2. llm.extract_flat_details(html, url) — Haiku tool-use call returns
       structured JSON (address, rooms, rent, description, pros/cons, etc.)
    3. Download each image directly to /data/flats/<slug>/NN.<ext>
    4. Persist enrichment_json + image_count + enrichment_status on the flat
- llm.py: minimal Anthropic /v1/messages wrapper, no SDK
- DB migration v5 adds enrichment_json/_status/_updated_at + image_count
- Admin "Altbestand anreichern" button (POST /actions/enrich-all) queues
  backfill for all pending/failed rows; runs in a detached task
- GET /partials/wohnung/<id> renders _wohnung_detail.html
- GET /flat-images/<slug>/<n> serves the downloaded image

UI
- Chevron on each list row toggles an inline detail pane (HTMX fetch on
  first open, hx-preserve keeps it open across the 3–30 s polls)
- CSS .flat-gallery normalises image tiles to a 4/3 aspect with object-fit:
  cover so different source sizes align cleanly
- "analysiert…" / "?" chips on the list reflect enrichment_status

Config
- ANTHROPIC_API_KEY + ANTHROPIC_MODEL wired into docker-compose's web
  service (default model: claude-haiku-4-5-20251001)

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

web/llm.py

@@ -0,0 +1,119 @@
+"""Minimal Anthropic Messages API wrapper for flat enrichment.
+
+Uses tool-use forced output so Haiku returns structured JSON instead of free
+text we'd have to regex. No SDK — plain `requests` is enough here.
+"""
+from __future__ import annotations
+
+import logging
+from typing import Any, Optional
+
+import requests
+
+from settings import ANTHROPIC_API_KEY, ANTHROPIC_MODEL
+
+logger = logging.getLogger("web.llm")
+
+API_URL = "https://api.anthropic.com/v1/messages"
+API_VERSION = "2023-06-01"
+
+TOOL_NAME = "record_flat_details"
+TOOL_SCHEMA: dict[str, Any] = {
+    "type": "object",
+    "properties": {
+        "address": {"type": ["string", "null"],
+                    "description": "Full street address incl. postcode+city if present"},
+        "rooms": {"type": ["number", "null"], "description": "Number of rooms (decimal ok)"},
+        "size_sqm": {"type": ["number", "null"], "description": "Size in m²"},
+        "rent_cold": {"type": ["number", "null"], "description": "Kaltmiete in €"},
+        "rent_total": {"type": ["number", "null"], "description": "Warm/Gesamtmiete in €"},
+        "utilities": {"type": ["number", "null"], "description": "Nebenkosten in €"},
+        "deposit": {"type": ["number", "null"], "description": "Kaution in €"},
+        "available_from": {"type": ["string", "null"], "description": "Bezugsfrei ab (text)"},
+        "floor": {"type": ["string", "null"], "description": "Etage (text, z.B. '3. OG')"},
+        "heating": {"type": ["string", "null"]},
+        "energy_certificate": {"type": ["string", "null"]},
+        "energy_value": {"type": ["string", "null"]},
+        "year_built": {"type": ["string", "null"]},
+        "wbs_required": {"type": ["boolean", "null"]},
+        "wbs_type": {"type": ["string", "null"], "description": "WBS-Typ, z.B. '160' oder null"},
+        "description": {
+            "type": ["string", "null"],
+            "description": "Kurze 2–3-Satz-Beschreibung der Wohnung auf Deutsch. Fakten, keine Werbesprache.",
+        },
+        "features": {
+            "type": "array", "items": {"type": "string"},
+            "description": "Ausstattungsmerkmale (z.B. 'Balkon', 'Einbauküche', 'Parkett')",
+        },
+        "pros": {
+            "type": "array", "items": {"type": "string"},
+            "description": "2–4 konkrete Vorteile aus Bewerbersicht (keine Werbung)",
+        },
+        "cons": {
+            "type": "array", "items": {"type": "string"},
+            "description": "2–4 mögliche Nachteile / Punkte zum Beachten",
+        },
+    },
+    "required": [],
+    "additionalProperties": False,
+}
+
+SYSTEM_PROMPT = (
+    "Du extrahierst strukturierte Wohnungsdaten aus deutschem HTML-Quelltext von "
+    "Berliner Wohnungsbaugesellschaften (howoge, gewobag, degewo, gesobau, wbm, "
+    "stadt-und-land). Antworte AUSSCHLIESSLICH über den bereitgestellten Tool-Call. "
+    "Fehlende Werte → null. Keine Erfindungen — wenn etwas nicht klar aus dem HTML "
+    "hervorgeht, lass das Feld null. Zahlen bitte als Zahlen (nicht als String), "
+    "Beschreibung/Pros/Cons auf Deutsch."
+)
+
+
+def extract_flat_details(html: str, url: str,
+                         max_html_chars: int = 60_000,
+                         timeout: int = 60) -> Optional[dict]:
+    """Call Haiku; return the structured dict or None on failure."""
+    if not ANTHROPIC_API_KEY:
+        logger.info("skipping enrichment: ANTHROPIC_API_KEY not set")
+        return None
+
+    user_content = (
+        f"URL: {url}\n\n"
+        f"HTML-Quellcode (ggf. gekürzt):\n---\n{html[:max_html_chars]}\n---"
+    )
+    body = {
+        "model": ANTHROPIC_MODEL,
+        "max_tokens": 1500,
+        "system": SYSTEM_PROMPT,
+        "tools": [{
+            "name": TOOL_NAME,
+            "description": "Persist the extracted flat details.",
+            "input_schema": TOOL_SCHEMA,
+        }],
+        "tool_choice": {"type": "tool", "name": TOOL_NAME},
+        "messages": [{"role": "user", "content": user_content}],
+    }
+    try:
+        r = requests.post(
+            API_URL,
+            headers={
+                "x-api-key": ANTHROPIC_API_KEY,
+                "anthropic-version": API_VERSION,
+                "content-type": "application/json",
+            },
+            json=body,
+            timeout=timeout,
+        )
+    except requests.RequestException as e:
+        logger.warning("anthropic request failed: %s", e)
+        return None
+
+    if r.status_code >= 400:
+        logger.warning("anthropic %s: %s", r.status_code, r.text[:300])
+        return None
+
+    data = r.json()
+    for block in data.get("content", []):
+        if block.get("type") == "tool_use" and block.get("name") == TOOL_NAME:
+            return block.get("input") or {}
+    logger.warning("anthropic returned no tool_use block: %s", data)
+    return None