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.

api/diagnostics.py

@@ -14,6 +14,29 @@ from typing import Dict, List, Tuple
 from mlos_sort import ModInfo
 
 
+# Filenames that legitimately appear across multiple mods because they're
+# intended merge points — either PZ engine-merged at runtime, or framework
+# extension hooks where multiple client mods coexist by design. Multiple
+# distinct sha1s here is by-design, not a conflict, so we skip them in
+# scan_file_conflicts. Sourced from HellDrinx Mod Manager's known false-
+# positive list (backend/services/workshop.cjs); add more here as we
+# encounter them.
+_IGNORED_FILENAMES = {
+    # PZ engine-merged at load time
+    "sandbox-options.txt",
+    "fileguidtable.xml",
+    # Framework extension hooks (designed for many mods to override)
+    "mf_ismoodle.lua",            # MoodleFramework hook
+    "kp_extrabodylocations.lua",  # KP body-locations framework hook
+    "registries.lua",             # damnlib-style registry framework
+    # Specific mod-side merge points
+    "hat_gasmask.xml",
+    "hat_gasmask_nofilter.xml",
+    "sounds_tmrremovemumble.txt",
+    "null.wav",                   # silent placeholder, deliberately shared
+}
+
+
 @dataclass
 class FileConflict:
     rel_path: str
@@ -59,7 +82,14 @@ async def scan_file_conflicts(conn, mods: List[ModInfo]) -> List[FileConflict]:
         idx = order_index.get(mod_id)
         if idx is None:
             continue
-        by_path[r["rel_path"]].append((idx, mod_id, r["sha1"]))
+        rel_path = r["rel_path"]
+        # Skip known intended-merge-point filenames (engine-concatenated or
+        # framework hooks). These produce noisy false positives because
+        # multiple mods adding sandbox vars / framework hooks is by design.
+        basename = rel_path.rsplit("/", 1)[-1]
+        if basename in _IGNORED_FILENAMES:
+            continue
+        by_path[rel_path].append((idx, mod_id, r["sha1"]))
 
     conflicts: List[FileConflict] = []
     for rel, entries in by_path.items():

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")