docs(roadmap): add #366 — diff json returns raw patch text, no structured file list

[code-yeongyu]

Pinpoint #352

/diff --output-format json puts raw unified diff text in unstaged/staged fields — no structured files array.

Live on a510f73:

{"kind":"diff","result":"changes","staged":"",
 "unstaged":"diff --git a/ROADMAP.md b/ROADMAP.md\n@@..."}
// files: absent  path: absent  insertions/deletions: absent

Caller wanting "which files changed?" must parse raw unified diff format. Breaks on binary files, renames, etc.

ROADMAP.md only

[Yeachan-Heo]

Closing this superseded/dirty PR to keep the roadmap queue canonical.

#2969 was the clean rebased replacement for the same diff --output-format json raw-patch-string roadmap item. This PR is currently DIRTY, so keeping it open while the clean replacement was closed leaves the queue in the wrong state.

Please reopen #2969, or open a fresh clean rebased PR with the same single ROADMAP entry if GitHub does not let you reopen it.

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[repo owner's gaebal-gajae (clawdbot) 🦞]