feat(create-plugin): add AI authoring assistance to panel-docs codemod

[sunker]

What this PR does / why we need it:

Adds AI authoring assistance to the panel-docs codemod: a conventions file the coding agent reads automatically, plus one bootstrap-plugin-docs skill for the initial fill.

The shape changed substantially from the first draft of this PR (four slash-command skills behind a required --agentLoop flag), after looking at what comparable tooling actually ships. Three findings drove it:

1. Conventions belong in always-loaded context, not in skills. Vercel's published evals found an auto-invoked skill scored no better than no docs at all (53% vs 53% baseline), because the skill was never invoked in 56% of cases, while always-loaded context scored 100%. Next.js states the same split as policy: context for lookups, skills for workflows.
2. Nobody ships per-agent skill fan-out. Of the tools surveyed (Nx, Next.js, Astro, Expo, React Router, Prisma, Supabase, Stripe, shadcn, Angular, Svelte), none hand-write parallel per-agent skill directories, and none ask which agent at scaffold time except Angular.
3. This repo already has the right pattern. templates/common/ scaffolds root AGENTS.md/CLAUDE.md/GEMINI.md pointers into .config/AGENTS/, with topic files like e2e-testing.md. This PR follows that rather than inventing a parallel convention.

Changes

• write-plugin-docs, review-plugin-docs and validate-plugin-docs are gone. The first two were conventions, the third wrapped npm run docs:validate. All three fold into the authoring guide.
• bootstrap-plugin-docs stays: it is a genuine multi-step workflow.
• The guide lands at .config/AGENTS/plugin-docs.md, next to e2e-testing.md, reached by a pointer line appended to .config/AGENTS/instructions.md.
• --agentLoop is replaced by --no-agents (defaults on).

Two things worth reviewing closely

The guide cannot live inside docsPath. It was at docs/AGENTS.md. Anything inside docsPath is validated as a publishable page, so npm run docs:validate failed on it with 8 errors. Moving it out fixes that, and the instructions.md pointer is also what makes it reachable from Claude Code, which never reads AGENTS.md.

The skill is written whole to both .claude/skills/ and .agents/skills/, not shimmed. The one-line @import shim pattern used by the existing build-plugin and validate-plugin skills does not work in Claude Code: the docs confirm @imports are unsupported in SKILL.md, and a SKILL.md whose first line isn't --- is treated as literal content, so such a skill registers no description and cannot be invoked. Duplication is deliberate: Context writes string content so symlinking isn't available, and these are committed team-shared files, so detecting the scaffolder's own agent would give their teammates the wrong answer. .agents/ covers Codex, Cursor, Copilot, Gemini CLI and Amp, so there is no separate .codex/ copy.

Which issue(s) this PR fixes:

N/A

Special notes for your reviewer:

Stacked on #2834, which must merge first.

Verified end to end against a scratch panel plugin: both skill copies are byte-identical and spec-valid (frontmatter present, name matches directory), every @-import in the instructions chain resolves, no {{placeholders}} leak, --no-agents writes the docs stubs and nothing else, and plugin-docs-cli validate --strict reports ✓ Documentation is valid.

Separately: the existing build-plugin and validate-plugin skills in templates/common/ are broken in Claude Code for the same reason described above. Out of scope here since fixing them changes what every new plugin gets.

[pkg-pr-new]

Open in StackBlitz

@grafana/create-plugin

npm i https://pkg.pr.new/grafana/plugin-tools/@grafana/create-plugin@ec5252f -D

@grafana/eslint-config

npm i https://pkg.pr.new/grafana/plugin-tools/@grafana/eslint-config@ec5252f -D

@grafana/eslint-plugin-plugins

npm i https://pkg.pr.new/grafana/plugin-tools/@grafana/eslint-plugin-plugins@ec5252f -D

@grafana/plugin-docs-cli

npm i https://pkg.pr.new/grafana/plugin-tools/@grafana/plugin-docs-cli@ec5252f -D

@grafana/plugin-docs-parser

npm i https://pkg.pr.new/grafana/plugin-tools/@grafana/plugin-docs-parser@ec5252f -D

@grafana/plugin-e2e

npm i https://pkg.pr.new/grafana/plugin-tools/@grafana/plugin-e2e@ec5252f -D

@grafana/plugin-meta-extractor

npm i https://pkg.pr.new/grafana/plugin-tools/@grafana/plugin-meta-extractor@ec5252f -D

@grafana/plugin-types-bundler

npm i https://pkg.pr.new/grafana/plugin-tools/@grafana/plugin-types-bundler@ec5252f -D

@grafana/react-detect

npm i https://pkg.pr.new/grafana/plugin-tools/@grafana/react-detect@ec5252f -D

@grafana/sign-plugin

npm i https://pkg.pr.new/grafana/plugin-tools/@grafana/sign-plugin@ec5252f -D

@grafana/tsconfig

npm i https://pkg.pr.new/grafana/plugin-tools/@grafana/tsconfig@ec5252f -D

commit: ec5252f

[sunker]

closing in favour of #2834