merge: conflict-blocklist filenames + path-based vehicle signal

Bring in two narrow additions previously sitting on a feature branch:

- api/diagnostics.py: \_IGNORED_FILENAMES skip-list for /api/conflicts.
  PZ engine-concatenated and framework-hook files (sandbox-options.txt
  etc.) ship with intentionally distinct sha1s across mods; they are
  not real conflicts. Live cache had 33 providers of sandbox-options.txt
  with 31 distinct hashes generating false-positive conflict rows.

- worker/build_manifest_and_types: extend the path-based Vehicles signal
  to include models_x/vehicles/ and models/vehicles/, catching mods that
  ship 3D vehicle assets without scripts. Existing mods need their
  manifest rebuilt before mod_types reflects the new signal.

worker/worker.py

@@ -365,7 +365,13 @@ def build_manifest_and_types(
                     or suffix in {".png", ".dds"}):
                 if path.name.lower() != "poster.png":
                     tags.add("Textures")
-            if rel_below.startswith(("scripts/vehicles/", "scripts/vehicle")):
+            # Path-based vehicle detection. scripts/vehicles is the universal
+            # signal; models[_x]/vehicles/ catches mods that ship 3D assets
+            # without scripts (rarer, but real — borrowed from HellDrinx Mod
+            # Manager's heuristic). rel_below is already lowercased so the
+            # capital "X" in the original PZ "models_X" path lands as "models_x".
+            if rel_below.startswith(("scripts/vehicles/", "scripts/vehicle",
+                                     "models_x/vehicles/", "models/vehicles/")):
                 tags.add("Vehicles")
             if rel_below.startswith(("clothing/", "scripts/clothing/")):
                 tags.add("Clothing")