feat(tool-call-mapping): emit compact file-edit diffs and raw io

[duclvz]

Summary

Replaces whole-file diff expansion in Codex file-change tool calls with the compact
per-hunk representation Codex actually sends, and populates the ACP tool_call
metadata fields that were previously left empty. This brings the adapter closer to
the ACP v1 tool-call contract and matches the behavior of other ACP adapters (e.g.
Claude Agent ACP).

What changed

• Hunk-local diff content — createUpdateFileContent now parses the unified
  patch and emits one diff content block per hunk with localized oldText and
  newText, instead of reading the source file and expanding to whole-file
  contents. Also drops the disk read entirely, so edits still render correctly
  when the source file is unavailable or already patched.
• locations — every file-change tool call now includes affected paths (and
  the first-hunk line number for updates / rename source + destination for moves).
• rawInput / rawOutput — the tool call carries the normalized
  FileUpdateChange[] as rawInput, and terminal updates carry
  { status, success } as rawOutput.
• item/fileChange/patchUpdated — previously ignored; now mapped to a
  tool_call_update carrying the refreshed hunks/locations while status stays
  in_progress.
• Session history replay — still emits a single completed tool_call for each
  historical file change; the snapshot now includes the new fields.

Test plan

• npm run typecheck
• npm test (288 passing)
• New regression coverage in file-change-events.test.ts:
  • invalid update patch → metadata preserved, content dropped
  • source file unavailable → still emits hunk-local diff
  • patchUpdated notification → compact content + metadata
  • start-before-completion ordering → no disk read on the in_progress emit

Notes

• Behavior is additive: consumers that only read content[] still see valid diff
  entries, just scoped to hunks instead of whole files.
• turn/diff/updated and item/fileChange/outputDelta remain intentionally
  ignored — the reproduced Codex 0.144 traffic did not emit them.