Bündel 2: Zentrale Helper für DRY-Cleanup, SW by-v1114

NEUE BACKEND-MODULE:

math_utils.py
- haversine_km(lat1, lon1, lat2, lon2) — Distanz in km
- haversine_m(...) — Convenience-Wrapper in Metern
- bbox_deg_from_km(lat, radius_km) — Bounding-Box-Approximation
  für SQL-Vorfilter (statt Haversine im Python-Loop)

config.py
- DB_PATH, MEDIA_DIR, BREEDER_DOCS_DIR, SCANINPUT_DIR
- API_TIMEOUT_SHORT (5s) / DEFAULT (10s) / LONG (30s)
- HTTP_USER_AGENT, HTTP_HEADERS

errors.py
- not_found(msg), forbidden(msg), bad_request(msg), unauthorized(msg)
- conflict(msg), too_many_requests(msg, retry_after), service_unavailable(msg)
- require_or_404(row, msg) — Convenience-Helper

UI.JS ERWEITERUNGEN:

UI.time erweitert:
- formatDate(d)     → "15.03.2026"
- formatDateTime(d) → "15.03.2026, 14:30"
- weekday(d)        → "Di"
- parseISO(str)     → {year, month, day}

UI.text (neu):
- truncate(str, maxLen, ellipsis='…')
- slug(str) — URL-Slug aus String (mit DE-Umlauten)

UI.money (neu):
- format(value) → "12,34 €" (de-DE, EUR)
- formatWithSuffix(value, '/Jahr')

HAVERSINE-MIGRATION (13 Backend-Routen):
alerts.py, services.py, places.py, events.py, diary.py, playdate.py,
lost.py, poison.py, adoption.py, gassi_zeiten.py, sitting.py, routen.py,
walks.py

- Alle lokalen def _haversine/haversine_km entfernt
- Aufrufe ersetzt durch haversine_km/haversine_m je nach Einheit
- from math_utils import haversine_km|haversine_m in jeder Datei

Tests 19/19 grün.

Hinweis: Migrationen für MEDIA_DIR (19 Stellen), API-Timeouts (12),
Date-Formatter im Frontend (24) und UI.text.truncate (5) sind als
Folge-Sprints möglich. Helper sind verfügbar.

backend/routes/adoption.py

@@ -10,7 +10,6 @@ Caching: adoption_cache Tabelle, 24h TTL.
 """
 
 import os
-import math
 import logging
 import asyncio
 import uuid
@@ -22,6 +21,7 @@ from typing     import Optional
 from database   import db
 from auth       import get_current_user
 from routes.push import send_push_to_user
+from math_utils import haversine_km
 
 MEDIA_DIR = os.getenv("MEDIA_DIR", "/data/media")
 
@@ -31,18 +31,6 @@ router = APIRouter()
 PETFINDER_KEY    = os.getenv("PETFINDER_API_KEY", "")
 PETFINDER_SECRET = os.getenv("PETFINDER_API_SECRET", "")
 
-# ------------------------------------------------------------------
-# Haversine — Distanz in km
-# ------------------------------------------------------------------
-def _haversine(lat1: float, lon1: float, lat2: float, lon2: float) -> float:
-    R  = 6371.0
-    p1 = math.radians(lat1)
-    p2 = math.radians(lat2)
-    dp = math.radians(lat2 - lat1)
-    dl = math.radians(lon2 - lon1)
-    a  = math.sin(dp / 2) ** 2 + math.cos(p1) * math.cos(p2) * math.sin(dl / 2) ** 2
-    return 2 * R * math.asin(math.sqrt(a))
-
 
 # ------------------------------------------------------------------
 # Statische Tierheim-Daten (große deutsche Tierheime)
@@ -234,7 +222,7 @@ async def adoption_nearby(
         for row in rows:
             d = dict(row)
             if d.get("tierheim_lat") and d.get("tierheim_lon"):
-                dist = _haversine(lat, lon, d["tierheim_lat"], d["tierheim_lon"])
+                dist = haversine_km(lat, lon, d["tierheim_lat"], d["tierheim_lon"])
                 if dist <= radius:
                     d["distanz_km"] = round(dist, 1)
                     cached_animals.append(d)
@@ -250,7 +238,7 @@ async def adoption_nearby(
     # ------ Statische Tierheime (immer) ------
     shelters = []
     for sid, name, plz, stadt, slat, slon, url in GERMAN_SHELTERS:
-        dist = _haversine(lat, lon, slat, slon)
+        dist = haversine_km(lat, lon, slat, slon)
         if dist <= radius:
             shelters.append({
                 "id":        sid,
@@ -354,7 +342,7 @@ def community_list(
         d = dict(row)
         d["user_interested"] = bool(d.pop("_user_interested", 0))
         if lat is not None and lon is not None and d.get("lat") and d.get("lon"):
-            dist = _haversine(lat, lon, d["lat"], d["lon"])
+            dist = haversine_km(lat, lon, d["lat"], d["lon"])
             d["distanz_km"] = round(dist, 1)
             if dist > radius:
                 continue