feat(graceful-handoff): initial plugin with /graceful-handoff command

New plugin that produces a complete session handoff in under 60s:
NEXT-SESSION artifact, commit+push, and copy-paste prompt for next
session. Built for context-constrained models like Opus 4.7 where
sessions fill fast.

- Single declarative command, no hooks/agents/skills
- Detects handoff type: multi-session / plugin-work / single-task
- Default filename NEXT-SESSION-PROMPT.local.md; slug-override
- Flags: --no-commit, --dry-run
- Auto-generated Conventional Commits message from git diff --stat
- Respects pre-commit hooks (secrets, pathguard) — never bypasses

Also: add *.local.md to root .gitignore (existing NEXT-SESSION files
were untracked but not ignored) and list plugin in marketplace
README + CLAUDE.md per docs-convention.

README.md

@@ -119,6 +119,26 @@ Research-informed thresholds. Alerts are progressive and never blocking. Privacy
 
 ---
 
+### [Graceful Handoff](plugins/graceful-handoff/) `v1.0.0`
+
+Session handoff in under 60 seconds. Built for context-constrained models like Opus 4.7 where sessions fill fast.
+
+When you hit 60-70% context and have to start a new session, three things usually get rushed or forgotten: summarizing state, committing finished work, and writing a continuation prompt. `/graceful-handoff` does all three in one step.
+
+- **Auto-detect handoff type** — multi-session (active ultraplan project), plugin-work (inside a marketplace plugin), or single-task (fallback)
+- **Writes `NEXT-SESSION-PROMPT.local.md`** — 7-section artifact (why, status, how to continue, push-policy, verification, gotchas) matching the established pattern in llm-security and config-audit
+- **Auto-commit + push** — generates Conventional Commits message from `git diff --stat`, respects pre-commit hooks (secrets, pathguard), pushes to Forgejo. `--no-commit` skips
+- **Copy-paste prompt for next session** — the critical output, always printed even if everything else fails
+- **No subagents, no web** — entirely inline in the main session, under 60 seconds budget
+
+Key command: `/graceful-handoff [topic-slug] [--no-commit] [--dry-run]`
+
+1 command · 0 hooks · 0 agents · declarative markdown
+
+→ [Full documentation](plugins/graceful-handoff/README.md)
+
+---
+
 ### [MS AI Architect — Azure AI and Microsoft Foundry](plugins/ms-ai-architect/) `v1.8.0` `🇳🇴 Norwegian`
 
 Microsoft AI solution architecture guidance for Norwegian public sector and enterprise.