fix: correct dict cursor access in MediaWiki import

Error: 500 Internal Server Error on execute import
Root cause: Using fetchone()[0] with RealDictCursor (dict-like rows)

PostgreSQL RealDictCursor returns dict-like objects, not tuples.
Accessing [0] on a dict throws TypeError.

Fix: Changed all fetchone()[0] to fetchone()['id']
Locations:
- Line 163: log_id after INSERT INTO wiki_import_log
- Line 485: ex_id after INSERT INTO exercises
- Line 599: skill_id after INSERT INTO skills
- Line 616: method_id after INSERT INTO training_methods

This matches the pattern used in other routers (exercises.py, etc.)

backend/routers/import_wiki.py

@@ -160,7 +160,7 @@ async def execute_import(
                RETURNING id""",
             (body.import_type, body.category, body.dry_run, body.reimport_existing, profile_id)
         )
-        log_id = cur.fetchone()[0]
+        log_id = cur.fetchone()['id']
         conn.commit()
 
     # Import asynchron starten
@@ -482,7 +482,7 @@ def _upsert_exercise(mapped: dict, reimport: bool) -> Optional[int]:
                     mapped.get("import_id"),
                 )
             )
-            ex_id = cur.fetchone()[0]
+            ex_id = cur.fetchone()['id']
 
         conn.commit()
 
@@ -596,7 +596,7 @@ def _upsert_skill(mapped: dict, reimport: bool) -> Optional[int]:
                RETURNING id""",
             (mapped["name"], mapped.get("description"), category_id)
         )
-        skill_id = cur.fetchone()[0]
+        skill_id = cur.fetchone()['id']
         conn.commit()
         return skill_id
 
@@ -613,7 +613,7 @@ def _upsert_method(mapped: dict, reimport: bool) -> Optional[int]:
                RETURNING id""",
             (mapped["name"], mapped.get("description"))
         )
-        method_id = cur.fetchone()[0]
+        method_id = cur.fetchone()['id']
         conn.commit()
         return method_id