Scene Manager: fixes from the first run against a real Libreflow

- Update / version switch: Blender 5.2 replaces the library on reload
  (renamed after its file, custom properties gone); find it by path and
  restore its name and tags.
- Remove the libraries an asset linked indirectly when it is removed or
  fails to load (remove_unused_libraries), never a managed one.
- Config: real Kitsu asset types for link modes and Shot Viewer groups,
  setdress_low files for bg_location, "environments" collection fallback.
- Dev fake server and test use the real asset types; rock links a node
  group from the essentials to cover the indirect library cleanup.
- README and CLAUDE.md updated with the live findings.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -312,7 +312,7 @@ The bottom of the panel lists the armatures of the scene, grouped into **Charact
 - **Shift+click**: adds it to the selection, to pose several rigs at once.
 - The rig(s) currently selected are highlighted.
 
-A rig loaded by the [Scene Manager](#scene-manager) is grouped by its Libreflow asset type (`chars` → Characters, `props` → Props, see `SHOT_VIEWER_ASSET_TYPE_GROUPS`). Otherwise, a rig counts as a character or a prop when its name, one of its collections, or the library file it comes from starts with `chr_` / `prp_` (see `SHOT_VIEWER_RIG_GROUPS` in [Configuration](#configuration)). Hidden rigs cannot be selected. Camera rigs (armatures carrying a camera) are not listed.
+A rig loaded by the [Scene Manager](#scene-manager) is grouped by its Libreflow asset type (`main_character`, `secondary_character`, `tertiary_character` → Characters; `main_props`, `secondary_props`, `vehicles` → Props; see `SHOT_VIEWER_ASSET_TYPE_GROUPS`). Otherwise, a rig counts as a character or a prop when its name, one of its collections, or the library file it comes from starts with `chr_` / `prp_` (see `SHOT_VIEWER_RIG_GROUPS` in [Configuration](#configuration)). Hidden rigs cannot be selected. Camera rigs (armatures carrying a camera) are not listed.
 
 ---
 
@@ -353,10 +353,10 @@ Lists the assets cast in the shot, with how many instances are loaded out of how
 
 **What gets loaded:**
 
-- **File:** the latest publish **available on this site** of the asset's first file matching `rigging/*.blend`, then `modeling/*.blend`.
-- **Collection:** from that file, `COL_<asset>`, else `<asset>`, else the file's only top-level collection.
-- **Characters and props** become **library overrides**, so animators can pose them. Other types, like sets, become **collection instances**.
-- **Where they go:** each asset type gets its own collection, `COL_chars`, `COL_props`, `COL_sets`…
+- **File:** the latest publish **available on this site** of the asset's first file matching `rigging/*.blend`, then `modeling/*.blend` (sets, `bg_location`: `setdress_low/*.blend`).
+- **Collection:** from that file, `COL_<asset>`, else `<asset>`, else `environments` (set dressing files), else the file's only top-level collection.
+- **Characters, props and vehicles** (`*_character`, `main_props`, `secondary_props`, `vehicles`) become **library overrides**, so animators can pose them. Other types, like sets and set props, become **collection instances**.
+- **Where they go:** each asset type gets its own collection, `COL_main_character`, `COL_main_props`, `COL_bg_location`…
 
 All of these can be changed in the [Configuration](#configuration).
 
@@ -460,7 +460,7 @@ Only markers bound to a camera are shots. Select the marker, select its camera,
 Start Libreflow (with the `wtdcmds` extension), then click the refresh icon of the Scene Manager. Its IPC server stops 30 seconds after the last Libreflow session closes.
 
 **Scene Manager: an asset cannot be loaded.**
-Its red line says why. "No file matching..." means none of its files matches `SCENE_MANAGER_FILE_PATTERNS`. "No collection named..." means the file has neither `COL_<asset>` nor `<asset>`, and several top-level collections: rename the published collection, or add its name to `SCENE_MANAGER_COLLECTION_NAMES`.
+Its red line says why. "No file matching..." means none of its files matches `SCENE_MANAGER_FILE_PATTERNS`. "No collection named..." means the file has none of `COL_<asset>`, `<asset>` or `environments`, and several top-level collections: rename the published collection, or add its name to `SCENE_MANAGER_COLLECTION_NAMES`.
 
 **Scene Manager: the version stays red after Update.**
 The newer version is published but not downloaded on this site yet. Wait for the sync, then update again.