enhancement(#782): emit gsd skills to ~/.cline/skills for Cline >= v3.48 (#809)

Cline added a global skills system (~/.cline/skills/<name>/SKILL.md) in
v3.48.0, but gsd treated Cline as rules-only and emitted zero skills
(getGlobalSkillsBase('cline')=null, empty artifact kinds). This makes gsd
emit skills for Cline at global scope, alongside the existing .clinerules.

- runtime-homes: getGlobalSkillsBase('cline') -> ~/.cline/skills (was null)
- runtime-artifact-layout: cline emits a skills kind for GLOBAL scope only
  (local stays .clinerules-only), mirroring claude's scope dispatch
- install.js: convertClaudeCommandToClineSkill emits name+description-only
  SKILL.md frontmatter (Cline/agentskills.io spec; no Claude-specific
  allowed-tools/argument-hint/agent), hyphen-normalized + .cline/-rewritten
  body; global cline routed through the skills path while .clinerules is
  still written; _applyRuntimeRewrites cline case handles custom
  CLINE_CONFIG_DIR; convertClaudeToCliineMarkdown also rewrites bare
  ~/.claude and CLAUDE_CONFIG_DIR
- docs: install-on-your-runtime.md documents Cline global skills vs local rules
- tests: converter (name+description-only), global emission, skills+.clinerules
  coexistence, scope-aware layout, custom-dir paths, idempotency

Closes #782

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

src/runtime-artifact-layout.cts

@@ -343,7 +343,7 @@ function resolveRuntimeArtifactLayout(runtime: string, configDir: string, scope:
       break;
 
     case 'cline':
-      kinds = [];
+      kinds = scope === 'global' ? [skillsKind('skills', 'gsd-', 'convertClaudeCommandToClineSkill', 'cline', configDir)] : [];
       break;
 
     case 'opencode':

src/runtime-homes.cts

@@ -11,9 +11,9 @@
  * Runtime-specific notes:
  *   hermes  — GSD skills nest under skills/gsd/<skillName>/ (not the flat
  *             skills/<skillName>/ layout used by all other runtimes).
- *   cline   — Rules-based; commands are embedded in .clinerules. Cline does
- *             not use a skills/ directory. getGlobalSkillDir() returns null
- *             for cline so the caller can emit an appropriate warning.
+ *   cline   — Skills-capable since v3.48.0 (#782). SKILL.md files live at
+ *             ~/.cline/skills/<skillName>/SKILL.md (same flat layout as cursor/codex).
+ *             .clinerules is also emitted (rules-based compatibility layer).
  */
 
 import os from 'node:os';
@@ -160,10 +160,9 @@ export function getGlobalConfigDir(runtime: string, explicitDir?: string | null)
  * Return the global skills base directory for the given runtime.
  * Most runtimes: <configDir>/skills
  * Hermes: <configDir>/skills/gsd  (nested category layout — #2841)
- * Cline:  null (rules-based, no skills directory)
+ * Cline ≥ v3.48.0: <configDir>/skills  (SKILL.md-based global skills — #782)
  */
 export function getGlobalSkillsBase(runtime: string): string | null {
-  if (runtime === 'cline') return null;
   if (runtime === 'hermes') {
     const configDir = getGlobalConfigDir(runtime);
     return path.join(configDir, 'skills', 'gsd');
@@ -180,7 +179,6 @@ export function getGlobalSkillsBase(runtime: string): string | null {
 
 /**
  * Return the full path to a specific skill's directory for the given runtime.
- * Returns null for runtimes that don't use a skills directory (cline).
  */
 export function getGlobalSkillDir(runtime: string, skillName: string): string | null {
   const base = getGlobalSkillsBase(runtime);