feat(integrations): add Grok Build skills-based integration (#3535)

* feat(integrations): add Grok Build skills-based integration

Add first-class support for xAI Grok Build via SkillsIntegration, installing
speckit skills under .grok/skills and wiring init/invocation/catalog surfaces.

Assisted-by: Grok Build (model: grok-4, supervised)

* test+docs: address Copilot review on Grok multi-install and next steps

Assert init next-steps guidance for Grok (.grok/skills, /speckit-*) and
clarify that multi-install safety is path/manifest isolation, not
agent-context defaults such as shared AGENTS.md.

* fix(integrations): Grok headless --always-approve and isolation paths

Document Grok multi-install isolation as .grok/skills and .grok/rules.
Override build_exec_args to pass --always-approve so non-interactive
dispatch is not blocked at tool permission gates.

* docs(integrations): list only managed .grok/skills for Grok isolation

Multi-install isolation documents Spec Kit-managed paths; Grok only
writes .grok/skills, so drop the read-only .grok/rules entry.

* fix(integrations): always-slash Grok hooks and refresh catalog date

Move grok to ALWAYS_SLASH_AGENTS so hooks never emit /speckit.plan when
ai_skills is missing/false. Update slash-format tests, persist ai_skills
on init, and bump catalog updated_at for the Grok entry.

---------

Co-authored-by: Nate Chadwick <1232206+natechadwick@users.noreply.github.com>
Co-authored-by: test <test@example.com>

.github/ISSUE_TEMPLATE/agent_request.yml

@@ -8,7 +8,7 @@ body:
       value: |
         Thanks for requesting a new agent! Before submitting, please check if the agent is already supported.
 
-        **Currently supported agents**: Amp, Antigravity, Auggie CLI, Claude Code, Cline, CodeBuddy, Codex CLI, Cursor, Devin for Terminal, Firebender, Forge, Gemini CLI, GitHub Copilot, Goose, Hermes Agent, IBM Bob, Junie, Kilo Code, Kimi Code, Kiro CLI, Lingma, Mistral Vibe, Oh My Pi, opencode, Pi Coding Agent, Qoder CLI, Qwen Code, RovoDev ACLI, SHAI, Tabnine CLI, Trae, ZCode, Zed
+        **Currently supported agents**: Amp, Antigravity, Auggie CLI, Claude Code, Cline, CodeBuddy, Codex CLI, Cursor, Devin for Terminal, Firebender, Forge, Gemini CLI, GitHub Copilot, Goose, Grok Build, Hermes Agent, IBM Bob, Junie, Kilo Code, Kimi Code, Kiro CLI, Lingma, Mistral Vibe, Oh My Pi, opencode, Pi Coding Agent, Qoder CLI, Qwen Code, RovoDev ACLI, SHAI, Tabnine CLI, Trae, ZCode, Zed
 
   - type: input
     id: agent-name

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -76,6 +76,7 @@ body:
         - Gemini CLI
         - GitHub Copilot
         - Goose
+        - Grok Build
         - Hermes Agent
         - IBM Bob
         - Junie

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -70,6 +70,7 @@ body:
         - Gemini CLI
         - GitHub Copilot
         - Goose
+        - Grok Build
         - Hermes Agent
         - IBM Bob
         - Junie