feat: Phase 3 manufacturing + firmware management

backend/firmware/models.py

@@ -0,0 +1,31 @@
+from pydantic import BaseModel
+from typing import Optional, List
+
+
+class FirmwareVersion(BaseModel):
+    id: str
+    hw_type: str        # "vs", "vp", "vx"
+    channel: str        # "stable", "beta", "alpha", "testing"
+    version: str        # semver e.g. "1.4.2"
+    filename: str
+    size_bytes: int
+    sha256: str
+    uploaded_at: str
+    notes: Optional[str] = None
+    is_latest: bool = False
+
+
+class FirmwareListResponse(BaseModel):
+    firmware: List[FirmwareVersion]
+    total: int
+
+
+class FirmwareLatestResponse(BaseModel):
+    hw_type: str
+    channel: str
+    version: str
+    size_bytes: int
+    sha256: str
+    download_url: str
+    uploaded_at: str
+    notes: Optional[str] = None