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.

plugins/graceful-handoff/CHANGELOG.md

@@ -0,0 +1,24 @@
+# Changelog
+
+All notable changes to graceful-handoff are documented here.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
+
+## [1.0.0] - 2026-04-19
+
+### Added
+
+- Initial release with single command `/graceful-handoff`
+- 6-fase deklarativ workflow: detect → classify → write artifact → update REMEMBER/TODO → commit+push → print copy-paste-prompt
+- Tre handoff-typer: `multi-sesjon` (ultraplan-prosjekt), `plugin-arbeid` (marketplace-plugin), `enkelt-oppgave` (fallback)
+- Default filnavn `NEXT-SESSION-PROMPT.local.md`; slug-override via første posisjons-argument
+- Flag: `--no-commit` (skip git), `--dry-run` (ingen skriving, ingen git-ops)
+- Auto-generert Conventional Commits-melding fra `git diff --stat`
+- Respekterer pre-commit hooks (secrets, pathguard) — bypasser aldri
+- Tidsbudsjett < 60 sekunder; ingen Agent-delegering, ingen WebSearch
+- 7-seksjons-template for NEXT-SESSION-artefakt (matcher eksisterende konvensjon i llm-security/config-audit)
+
+### Notes
+
+- Auto-discover plugin — `marketplace.json`-oppføring ikke nødvendig
+- MIT-lisens