Add clear asset GPS endpoint + UI

- DELETE /api/assets/{id}/gps: clears lat/lng to NULL
- GET /api/assets/{id}: asset lookup by ID
- GET /api/assets/search?machine_id=: asset lookup by machine ID
- Export & Admin page: Clear Asset GPS card with lookup + confirmation
- Tests: 204 success + 404 not found

test_admin_crud.py

@@ -288,3 +288,32 @@ class TestSettings:
         cid = _assert_created(client.post("/api/settings/categories", json={"name": name}), "category")
         resp = client.delete(f"/api/settings/categories/{cid}")
         assert resp.status_code == 204
+
+
+# ─── Asset GPS ──────────────────────────────────────────────────────────────
+
+class TestClearAssetGps:
+    def test_clear_gps_returns_204(self, client):
+        """Clear GPS returns 204 and sets lat/lng to null."""
+        # Create an asset with GPS coords via direct DB insert
+        import sqlite3
+        conn = sqlite3.connect(DB_PATH)
+        conn.execute(
+            "INSERT INTO assets (machine_id, name, latitude, longitude) VALUES (?, ?, ?, ?)",
+            ("GPS-ADMIN-TEST", "Test GPS Asset", 28.5, -81.3),
+        )
+        asset_id = conn.execute("SELECT last_insert_rowid()").fetchone()[0]
+        conn.commit()
+        conn.close()
+
+        resp = client.delete(f"/api/assets/{asset_id}/gps")
+        assert resp.status_code == 204
+
+        # Verify
+        data = _assert_ok(client.get(f"/api/assets/{asset_id}"), "asset")
+        assert data["latitude"] is None
+        assert data["longitude"] is None
+
+    def test_clear_gps_not_found_returns_404(self, client):
+        resp = client.delete("/api/assets/99999/gps")
+        assert resp.status_code == 404