Social: Trainingstipp-Generator, Übungen in DB, 3 Stil-Varianten

- training_exercises Tabelle mit 13 Übungen aus App-Bibliothek
- POST /social/training-tip: Stil-Varianten tutorial/community/aspirational
- exercise_id in social_content für Wiederholungs-Tracking
- Admin-Stats: Social-Media-Sektion mit Status-Übersicht + letzte 10 Posts
- SW by-v349, APP_VER 336

backend/database.py

@@ -561,12 +561,35 @@ def _migrate(conn_factory):
                 published_at    TEXT,
                 source          TEXT    NOT NULL DEFAULT 'generated',
                 breed_id        INTEGER REFERENCES wiki_rassen(id) ON DELETE SET NULL,
-                notes           TEXT
+                coaching        TEXT,
+                notes           TEXT,
+                media_url       TEXT,
+                category        TEXT,
+                exercise_id     TEXT
             );
             CREATE INDEX IF NOT EXISTS idx_social_content_status
                 ON social_content(status);
         """)
 
+        # Training-Übungen (für Social Media + Auswertung)
+        conn.executescript("""
+            CREATE TABLE IF NOT EXISTS training_exercises (
+                id              INTEGER PRIMARY KEY AUTOINCREMENT,
+                exercise_id     TEXT    NOT NULL UNIQUE,
+                name            TEXT    NOT NULL,
+                kategorie       TEXT    NOT NULL,
+                schwierigkeit   TEXT,
+                alter_ab        TEXT,
+                dauer           TEXT,
+                beschreibung    TEXT,
+                schritte        TEXT,
+                tipp            TEXT,
+                created_at      TEXT    NOT NULL DEFAULT (datetime('now'))
+            );
+            CREATE INDEX IF NOT EXISTS idx_training_exercises_kat
+                ON training_exercises(kategorie);
+        """)
+
         # Knigge: Community-Votes
         conn.executescript("""
             CREATE TABLE IF NOT EXISTS knigge_votes (