feat(#787): elevate Cline — .clinerules/ dir form, PreToolUse hook, AGENTS.md (#803)

* feat(#787): elevate Cline — .clinerules/ dir form, PreToolUse hook, AGENTS.md

Migrate the installer's Cline output from a single-file .clinerules to the
.clinerules/ directory form (.clinerules/gsd.md), which is the prerequisite for
Cline's v3.36 hooks (a path cannot be both a file and a directory). Add a
.clinerules/hooks/PreToolUse lifecycle hook implementing Cline's JSON stdin ->
{cancel,errorMessage,contextModification} protocol; it guards .planning/
artifacts and fails open. On global installs, merge GSD instructions into the
cross-tool ~/.agents/AGENTS.md target (marker-delimited, merge-safe). A legacy
single-file .clinerules is migrated in place; --uninstall removes the new
artifacts and strips the AGENTS.md GSD block.

Also fixes the uninstall targetDir for Cline local installs (it pointed at
./.cline instead of the project root) and re-runs writeManifest after the
Cline artifacts are written so they are hash-tracked.

Self-contained: implemented independently of the #782 Cline skills work.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* fix(#787): address review findings

- Scope PreToolUse hook path-walk to PATH_KEY fields only (eliminates false
  positive when doc body content mentions .planning/)
- Use lstatSync + isSymbolicLink() for migration guard so GSD never writes
  through a user's symlinked .clinerules into an external directory
- Add regression tests for both cases

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* chore(#787): set changeset pr: 803

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

docs/how-to/install-on-your-runtime.md

@@ -205,7 +205,7 @@ WINDSURF_CONFIG_DIR=~/.codeium/windsurf-alt npx @opengsd/gsd-core@latest --winds
 
 ### Cline
 
-Cline uses a rules-based integration — GSD installs as `.clinerules` rather than slash commands.
+Cline uses a rules-based integration — GSD installs as Cline rules rather than slash commands.
 
 ```bash
 # Global install (all projects)
@@ -215,7 +215,24 @@ npx @opengsd/gsd-core@latest --cline --global
 npx @opengsd/gsd-core@latest --cline --local
 ```
 
-Global installs write to `~/.cline/`. Local installs write to `./.cline/`. Rules are loaded automatically by Cline — no custom slash commands are registered.
+GSD writes the [`.clinerules/` directory form](https://docs.cline.bot/customization/cline-rules):
+
+- **`.clinerules/gsd.md`** — the GSD rule file. Cline loads every `.md`/`.txt` file in
+  the `.clinerules/` directory automatically; no custom slash commands are registered.
+- **`.clinerules/hooks/PreToolUse`** — a [lifecycle hook](https://cline.bot/blog/cline-v3-36-hooks)
+  (Cline v3.36+). It is an executable script that receives the tool-call context as JSON on
+  stdin and returns a JSON decision (`cancel` / `errorMessage` / `contextModification`). The
+  GSD hook guards `.planning/` artifacts from direct edits and otherwise allows the operation;
+  it fails open, so a hook error never blocks you. Cline runs hooks on macOS and Linux only.
+
+Global installs additionally merge GSD instructions into **`~/.agents/AGENTS.md`**, the
+cross-tool global instruction file Cline reads. The block is marker-delimited, so your own
+`AGENTS.md` content (and other tools' entries) is preserved, and `--uninstall` strips only the
+GSD block.
+
+> Cline's *global* hook directory (`~/Documents/Cline/Rules/Hooks/`) is not yet populated by the
+> installer — project-scope hooks (`.clinerules/hooks/`) and the global `AGENTS.md` instruction
+> target cover the common cases.
 
 ---