Verify docs/PLUGINS.md against the plugin loader

[TheGreatAxios]

Summary: Apply five Shakespeare-verified corrections to docs/PLUGINS.md (W1, W2, W3, M1, C2). Docs text only; no behavior files touched.

Verification: spot-checked each fix against code anchors (src/config/settings.ts, src/plugins/loader.ts, src/plugins/data-only.ts, src/plugins/origin-marker.ts, src/tui/command-surfaces.ts); pre-commit gate passed.

Fixes CL-7897

[linear-code]

CL-7897

[TheGreatAxios]

Review · Approve

Verifies docs/PLUGINS.md against the plugin loader; each corrected statement matches code.

Findings (spot-checks, all pass)

• `src/plugins/loader.ts:165-194` — metadata-only path reads native `manifest.json` or `.claude-plugin/manifest.json` only (`readClaudeFormatManifestJson`), never `plugin.json`; kind hardcoded `"command"` (`loader.ts:156`). Doc correction accurate.
• `src/plugins/data-only.ts:122-173` + `readClaudePluginManifest` (`data-only.ts:107-120`) — full-load `loadDataOnlyPlugin` prefers native manifest, then `plugin.json`, then manifest variant, inferring kind. Parenthetical accurate.
• `src/config/settings.ts:903-911` — `workflowPlugins`/`agentPlugins` warn on load and are absent from the saved `optional` set (dropped on next save); no aliasing into `pluginPaths`. Old back-compat sentence was wrong; replacement is correct.
• `src/plugins/origin-marker.ts:11-17` + `src/tui/command-catalog.ts:42` — origin `repo` renders `[bundled]`, others `[user]`/`[project]`/`[path]`; same marker applied to slash-command picker labels. Accurate.
• `src/tui/command-surfaces.ts:1033-1035` — add-by-path is Alt+A, not `a`. Accurate.
• `src/extensions/skills.ts:165-168` + `src/plugins/skill-commands.ts:14-16` — `disable-model-invocation` skills are omitted from `discoverSkills` listing but still load via explicit `use_skill`/`resolveSkillBody`. Accurate.

Nits (non-blocking)

• The `loadDataOnlyPlugin` parenthetical sits inside the metadata-only sentence; a reader may briefly conflate the two paths. Consider a standalone sentence for the full-load path. Not merge-blocking.

No blocking issues. Merge-ready.