docs(tools): DiffResultView.diffs may be a whole-file diff, not only hunks

The write-diff-card fix made write's presentResult return an args-derived
whole-file diff (oldText:null) for a create / unchanged overwrite, but the
DiffResultView contract and its mirrored docs still said `diffs` is ALWAYS
the applied contextual hunks computed from before/after. Correct the type
JSDoc, the write execute-side comment, and the four mirrored surfaces
(tools.md, tools README, acp-feature-support, adding-a-tool cookbook) to
say: typically the applied hunks, or a whole-file diff when there is no
before-image (a create) — and that a mutation returns the diff result even
when it duplicates the call-time card, since a tool_call_update.content
replace would otherwise clobber the diff with the model-facing text.
Regenerate the cordis catalog (source line shift).

packages/fs/tool-fs/src/write.ts

@@ -62,9 +62,10 @@ export function applyWriteTool(ctx: Context): void {
       const outcome = await ctx.fs.writeText(target, input.content, intent, exec.signal)
       // Record the observed version (a no-op when no policy plugin listens).
       ctx.emit('fs/observed', target, outcome.version, exec)
-      // Result-time contextual diff ONLY for an overwrite (a before-version
+      // Attach a contextual hunk as `meta` ONLY for an overwrite (a before-version
       // exists). A create has no "before" — `outcome.before` is null — so it
-      // carries no result diff, leaving just the call-time whole-file card.
+      // carries no `meta`; `presentResult` then renders a whole-file diff from the
+      // args, so the completed card is still a diff (never the result text).
       const diffs = outcome.before !== null ? computeHunkDiffs(input.filePath, outcome.before, outcome.after) : []
       return {
         content: [{ type: 'text', text: formatWriteOutput(target.displayPath, outcome) }],