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-local/src/fsio.ts

@@ -429,4 +429,4 @@ export function applyLiteralEdit(
   return { content: content.split(oldNorm).join(newNorm), replacements }
 }
 
-export { restoreLineEndings }
+export { normalizeLineEndings, restoreLineEndings }

packages/fs/fs-local/src/index.ts

@@ -26,6 +26,7 @@ import type {
 } from '@deepseek-ai/dsh-fs'
 import {
   applyLiteralEdit,
+  normalizeLineEndings,
   probe,
   readForEdit,
   readTextForDiff,
@@ -156,7 +157,10 @@ export class LocalFileSystem extends FileSystem {
         operation: existing ? 'update' : 'create',
         version: this.versionAfterWrite(after, target),
         before,
-        after: content,
+        // LF-normalized to share the diff basis with `before` (also LF): a CRLF
+        // overwrite must not read as every line changed. Line-ending restoration
+        // is a storage detail the applied-hunk diff ignores.
+        after: normalizeLineEndings(content),
       }
     })
   }

packages/fs/fs-local/tests/filesystem.spec.ts

@@ -203,11 +203,15 @@ describe('writeText', () => {
     expect(outcome.after).toBe('new body')
   })
 
-  it('an overwrite of a CRLF file returns LF-normalized before content', async () => {
-    await writeFile(join(dir, 'a.txt'), 'a\r\nb\r\n')
+  it('an overwrite returns LF-normalized before AND after (a CRLF rewrite is not every-line-changed)', async () => {
+    // The applied-hunk diff bases on `before`/`after`; if `after` kept CRLF while
+    // `before` is LF-normalized, a CRLF rewrite would read as every line changed.
+    // Both sides are LF so only the genuinely-changed line diffs.
+    await writeFile(join(dir, 'a.txt'), 'a\r\nb\r\nc\r\n')
     const target = await fs.resolve('a.txt')
-    const outcome = await fs.writeText(target, 'a\nB\n')
-    expect(outcome.before).toBe('a\nb\n')
+    const outcome = await fs.writeText(target, 'a\r\nB\r\nc\r\n')
+    expect(outcome.before).toBe('a\nb\nc\n')
+    expect(outcome.after).toBe('a\nB\nc\n')
   })
 
   it('an overwrite of a BINARY prior file reports before:null (undiffable), still succeeds', async () => {