Add per-movie attributes and per-category filename templates

PROJECT.md

@@ -102,6 +102,28 @@ movie table, and one-click Filmotéka generation.
   `HardlinkManager` supports an empty root (tag folders placed directly at the
   output root) and restricts obsolete cleanup to the tag-tree's own top-level
   folders so mirrors are never touched.
+- **Tag schema (config-driven, not hard-coded):** the categories, their ČSFD
+  source field + transform, and their Filmotéka folder mapping all live in
+  `tag_schema` in the global config (default `config.DEFAULT_TAG_SCHEMA`, edited
+  via *Nastavení → Tag schéma…*). Both `apply_csfd_tags` (which fields → tags)
+  and the Filmotéka layout (`FileManager.filmoteka_category_roots`) read from it,
+  so adding a category or changing a folder rule needs no code change. A category
+  can be made filter-only (no folders) by setting its `filmoteka_root` to null.
+  The `transform` (e.g. `decade_band`) shapes only the **folder name** — tags keep
+  the **exact value** (rating → tag `Hodnocení/90`, folder `Dle hodnocení/90–100 %`);
+  it is applied at Filmotéka generation via `filmoteka_category_transforms`.
+- **Per-category filename template** (`filename_template` in a schema entry): the
+  hardlink name **inside that category's folders only** is rendered from the
+  movie's metadata (`File.name_context`: title/year/rating/ext/stem/filename plus
+  any free-form attributes), e.g. a Kolekce with `"{collection_sort} - {title}{ext}"`.
+  Other folders and the pool file keep the plain name; applied via
+  `filmoteka_category_filename_templates`.
+- **Free-form per-movie attributes** (`File.attributes`, set in the GUI): arbitrary
+  `key → value` metadata stored in the index and merged into `name_context`, so
+  custom fields like `collection_sort` can drive filename templates.
+- **Tag provenance (ČSFD vs user):** each file records which tags came from ČSFD
+  (`csfd_tags`). Re-fetching regenerates only those; user-added tags are kept, so
+  changing a movie's ČSFD link refreshes ČSFD tags without losing manual ones.
 
 ## Tasks