refactor(fs): minimize and cap search card meta; keep TUI byte-identical

Address the review of the search render card:

- The search result view carries no `content`: it was a no-op for every
  consumer and serialized the whole search text twice. A UI without a search
  card falls back to the raw tool/result content; the TUI stays byte-identical
  to the pre-search-card generic fallback.
- Bound the serialized presentationMeta with a configurable searchMetaMaxBytes
  (default 64 KiB): the inline item cap does not bound bytes, and spill-policy
  only shrinks content, never meta. capMetaBytes drops trailing groups/paths.
- Share one retention pass (retainGrepMatches/retainGlobPaths in search-core)
  between the model-facing render and the meta projection; remove the second
  cap/preview implementation and the presentation<->grep module cycle by
  moving GrepMatch/previewLine to search-core.
- Rename the result-view discriminant kind -> shape so it no longer collides
  with GenericCallView.kind (ToolCallKind, whose values include 'search').
- Narrow the entry export surface to consumed symbols.
- Sync the three bilingual ToolResultView doc pairs and the Agent Note pair;
  document the deliberate empty-card acceptance vs diffsFromMeta.
- Regenerate config/tool/cordis catalogs for the new config field.

docs/cookbook/adding-a-tool.md

@@ -78,6 +78,7 @@ Both methods return a **`card`-tagged render intent** — pick the card kind tha
   - `generic` supplies an optional title and content.
   - `terminal` supplies raw output and optional exit metadata; each UI renders its capable or fallback view.
   - `diff` supplies applied hunks, often derived by `output.presentationMeta` and carried in persisted `result.meta` so replay reproduces them. Mutation tools keep a diff result because the completed view replaces the pending card.
+  - `search` supplies a discovery result reconstructed from persisted `result.meta`: grouped-by-file matches (`shape: 'matches'`, grep) or a flat path list (`shape: 'paths'`, glob), plus `truncated`/`total` so a UI never presents a capped result as complete. The view carries no result text (a UI without a search card falls back to the raw result content), and there is no `search` call view — a discovery call's pending state stays a generic card, since matches exist only after `execute`. (tool-fs-search `grep`/`glob`.)
 
 Hard rules (they bite if broken):