feat: admin scenario PDF download + business plan export tests

Add /scenarios/<id>/pdf admin route for direct PDF generation via WeasyPrint.
Fix plan.html Jinja template: .items → ['items'] to avoid dict method collision.
Add scenario fixture in conftest.py and comprehensive test suite for business
plan sections, PDF generation, worker handler, and export routes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/tests/conftest.py

@@ -141,6 +141,25 @@ def create_subscription(db):
     return _create
 
 
+# ── Scenarios ────────────────────────────────────────────────
+
+@pytest.fixture
+async def scenario(db, test_user):
+    """User scenario with valid planner state for PDF generation."""
+    import json
+    from padelnomics.planner.calculator import validate_state
+    state = validate_state({"dblCourts": 4, "sglCourts": 2})
+    now = datetime.utcnow().isoformat()
+    async with db.execute(
+        """INSERT INTO scenarios (user_id, name, state_json, created_at)
+           VALUES (?, 'Test Scenario', ?, ?)""",
+        (test_user["id"], json.dumps(state), now),
+    ) as cursor:
+        scenario_id = cursor.lastrowid
+    await db.commit()
+    return {"id": scenario_id, "state": state, "user_id": test_user["id"]}
+
+
 # ── Config ───────────────────────────────────────────────────
 
 @pytest.fixture(autouse=True)