fix(tool-fs): CRLF-safe write diff, opaque meta, doc sync

Address the applied-hunk-diffs review:

- CRLF write overwrite emitted bogus every-line-changed hunks: write's
  `before` was LF-normalized but `after` kept the raw model content, so a
  CRLF rewrite of an LF file diffed every line. Normalize write's `after`
  to LF so both sides share the diff basis (edit already did). Regression
  test proves it fails on the raw-after path.
- The tool-private `meta` payload is now typed `unknown` (opaque) at every
  seam instead of `JsonValue`. This drops the `dsh-tools -> dsh-session`
  package edge that existed only to name the type, and removes the
  `FileDiff` index signature that had been widening the type solely for
  JsonValue-assignability. Serializability is still enforced at runtime by
  `Session.append`'s isJsonValue check, which was always the real guard.
- Sync the docs the new result/meta surface left stale: ToolResultView's
  diff card + ToolExecutionResult.meta in tools.md/session.md type-equiv
  blocks, the acp/tools READMEs, and the adding-a-tool cookbook; regenerate
  the cordis catalog and module graph.

packages/fs/fs/src/types.ts

@@ -103,11 +103,11 @@ export interface FsWriteOutcome {
   version: FsVersion
   /**
    * The file's content BEFORE the write, or `null` when the file did not exist
-   * (a create). Raw storage text (LF-normalized by the backend), never a diff —
-   * a consumer computes the result-time contextual diff from `before`/`after`.
+   * (a create). LF-normalized storage text (the diff basis), never a diff — a
+   * consumer computes the result-time contextual diff from `before`/`after`.
    */
   before: string | null
-  /** The file's content AFTER the write (the text that was written). */
+  /** The file's content AFTER the write, LF-normalized to share `before`'s diff basis. */
   after: string
 }