OSM-Beiträge: dog=yes-Erfassung mit GPS/Zeit-Anti-Fraud + Gamification-Zähler

- Tabelle osm_contributions (status pending→submitted→confirmed/rejected).
- Router /api/osm-contrib: POST /dog-friendly (Anti-Fraud: GPS-Beleg über
  kürzliche eigene Tour ≤50m + Verweil-Proxy, Tour-Recency 48h, Tages-Cap,
  Dedup, Positions-Sanity), GET /status (Zähler).
- Settings-UI: Zähler "X Orte eingetragen · noch Y bis Badge/Pro".
- OSM-Changeset-Upload + Pro-Freischaltung + Geräte-Attestierung folgen separat.

backend/database.py

@@ -368,6 +368,30 @@ def init_db():
             linked_at  TEXT    NOT NULL DEFAULT (datetime('now'))
         );
 
+        -- OSM-Beiträge ("Hund war willkommen" → dog=yes). Anti-Fraud: GPS-Beleg
+        -- über eine kürzliche eigene Tour (route_id) + Zeit/Rate-Limits.
+        -- status: pending → submitted (an OSM) → confirmed (Revert-überlebt) | rejected.
+        CREATE TABLE IF NOT EXISTS osm_contributions (
+            id              INTEGER PRIMARY KEY AUTOINCREMENT,
+            user_id         INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+            osm_id          INTEGER NOT NULL,
+            osm_type        TEXT    NOT NULL DEFAULT 'node',   -- node | way
+            poi_type        TEXT,
+            tag_key         TEXT    NOT NULL DEFAULT 'dog',
+            tag_value       TEXT    NOT NULL DEFAULT 'yes',
+            lat             REAL,
+            lon             REAL,
+            route_id        INTEGER REFERENCES routes(id) ON DELETE SET NULL,
+            gps_distance_m  REAL,
+            gps_points_near INTEGER,
+            status          TEXT    NOT NULL DEFAULT 'pending',
+            created_at      TEXT    NOT NULL DEFAULT (datetime('now')),
+            submitted_at    TEXT,
+            changeset_id    INTEGER,
+            UNIQUE(user_id, osm_id, tag_key)
+        );
+        CREATE INDEX IF NOT EXISTS idx_osm_contrib_user ON osm_contributions(user_id, status);
+
         -- VERLORENE HUNDE
         CREATE TABLE IF NOT EXISTS lost_dogs (
             id           INTEGER PRIMARY KEY AUTOINCREMENT,