Complete M11 Creator Studio and M12 Trust & Safety for PC5

- Creator Studio: Visual behavior & property inspector, GLB model importer, binary persistence
- Trust & Safety: 18+ TOS confirmation (DOB removed), creator guidelines & briefing card on join, in-game reporting HUD
- Test Harness: Add --filter, --skip-backend, --skip-godot to run_checkpoint_tests.py

backend/app/routers/chat_reports.py

@@ -124,9 +124,42 @@ async def report_message(
     return report
 
 
+class ModerationReportCreate(BaseModel):
+    target_type: Literal["message", "world", "user"]
+    target_id: int
+    reason: str = Field(..., min_length=1, max_length=500)
+    category: str | None = Field(default="general", max_length=50)
+
+
 # ──────────────────────────────── Moderation ────────────────────────────────────
 
 
+@moderation_router.post(
+    "/reports",
+    response_model=MessageReportResponse,
+    status_code=status.HTTP_201_CREATED,
+)
+async def submit_moderation_report(
+    payload: ModerationReportCreate,
+    current_user: CurrentUser,
+    db: DbDep,
+):
+    """Submit a moderation report for a world, user, or chat message."""
+    report_reason = f"[{payload.target_type.upper()}:{payload.target_id}] [{payload.category}] {payload.reason}"
+    msg_id = payload.target_id if payload.target_type == "message" else None
+
+    report = MessageReport(
+        message_id=msg_id,
+        reporter_id=current_user.id,
+        reason=report_reason,
+        status=ReportStatus.OPEN,
+    )
+    db.add(report)
+    await db.commit()
+    await db.refresh(report)
+    return report
+
+
 @moderation_router.get("/reports", response_model=list[MessageReportResponse])
 async def list_reports(
     current_user: CurrentUser,
@@ -146,6 +179,7 @@ async def list_reports(
     return list(result.scalars().all())
 
 
+
 @moderation_router.post(
     "/reports/{report_id}/resolve",
     response_model=ResolveReportResponse,