feat(antigravity): update placemat for Antigravity CLI v1.3.1

[dommango]

What this changes

Syncs five vendor releases (v1.2.15 through v1.3.1) that landed since the placemat's last sync (v1.2.14, 2026-09-30). Pulled from antigravity.google/docs/changelog's hidden id="panel-cli" tab panel, cross-checked against the required /download#antigravity-cli link href and the "Latest" tag on v1.3.1.

Highlights: /diff cross-file navigation and the new change A/B · file X/Y position indicator, /resume and /rewind fixes, Windows /plugin MCP-server lifecycle handling plus UTF-8 BOM support for plugin/MCP/hook config files, subagent error states and the built-in image-generator subagent, verbosity defaulting to medium, several Vim-mode and queued-message fixes, and notes on useG1Credits, notifications, CLI_GRAPHICS, and GEMINI_API_KEY.

No new slash commands, settings keys, or hook events appeared in these releases (confirmed against a fresh cli/reference fetch), so sources.json → inventory.fetched is unchanged, and no previously-unverified item (/effort, queuedMessages, --remote-control, the word-motion keybindings) got promoted — cli/reference still doesn't document any of them.

Type

• Content correction (wrong/outdated/missing entry)

Checklist

• I read AGENTS.md's Style Guide and Content Rules
• node tests/placemat.test.js passes locally (218 passed, 0 failed)
• node scripts/build-changes.js --all --check passes locally (generated files are fresh)
• No versions/*.html files were edited
• No hand-edited changes.json or feed.xml — both are generator output (build-changes.js antigravity)
• Every new/changed row is sourced from Antigravity's own vendor docs/changelog — never copied from a sibling placemat
• Anything I could only infer carries class="unverified" (none newly added or removed this sync)
• N/A — no new rows added this sync (only notes on existing rows), so no new id="i-<slug>" needed
• Only the antigravity/ directory is touched

Source

• https://antigravity.google/docs/changelog (id="panel-cli", releases rel-cli-1.2.15 through rel-cli-1.3.1)
• https://antigravity.google/docs/cli/reference (re-fetched to re-check unverified items and rule out new commands/settings/hooks)

🤖 Generated with Claude Code

https://claude.ai/code/session_01QXsAD145jQ67XVANd24S3n

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Generated by Claude Code

[dommango]

Merge gate: code-review verdict

Independent code-review pass (medium effort) against this PR's diff — separate from the Step 8 self-review in the pipeline.

No CRITICAL/HIGH findings.

Checked: every changelog entry maps to the right card-* id and row; all +N notes-btn labels recounted against their <li> counts; header .release-tag, .print-head, and footer sync date all agree at v1.3.1 / 2026-10-07; only the October month-group is open with a correct 5-release count and monotonic version ordering; no hand-written class="new", no silently-promoted unverified rows, no changed row ids, no new rows (so no inventory bump needed); only antigravity/ touched. node tests/placemat.test.js antigravity (54 passed) and node scripts/build-changes.js --all --check (up to date) both green.

Per the merge gate in antigravity/PIPELINE.md Step 10: proceeding to merge once CI is green.

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Generated by Claude Code