feat(vibe): migrate to SkillsIntegration from the old prompts-based MarkdownIntegration

[Fango2007]

PR purpose : Updating Mistral Vibe integration

Since v2.0.0, Mistral Vibe supports custom slash commands through skills system https://github.com/mistralai/mistral-vibe#custom-slash-commands-via-skills

Summary of changes

Switches VibeIntegration from the old prompts-based MarkdownIntegration to SkillsIntegration, adopting the .vibe/skills/speckit-/SKILL.md layout required by Mistral Vibe v2.0.0+.
Post-processes each generated SKILL.md to inject user-invocable: true so skills are directly callable by users, not just by other agents.

Testing

• Tested locally with uv run specify --help
• Ran existing tests with uv sync && uv run pytest

uv run python -m pytest tests/test_agent_config_consistency.py -q
(specify-cli) MacBook-Pro:spec-kit *$ uv run python -m pytest tests/test_agent_config_consistency.py -q
============================== test session starts =========================
platform darwin -- Python 3.12.12, pytest-9.0.3, pluggy-1.6.0
rootdir: /Users/*/*/Projects/codebase/clone/spec-kit
configfile: pyproject.toml
plugins: cov-7.1.0
collected 24 items                                                                                                                                                                                                                                         

tests/test_agent_config_consistency.py ........................    [100%]
================ 24 passed in 0.06s =======================================

• Manual test results

**Agent**: [Vibe]  |  **OS/Shell**: [macOS/zsh]

| Command tested | Notes |
|----------------|-------|
| `/speckit.constitution` | OK |
| `/speckit.specify` | OK |

• AI review
• Required tests: all passed

┌───────────────────────────────────────────────┬───────────────────────┬──────┬────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐   
  │                 Changed file                  │        Affects        │ Test │                                                                                          Why                                                                                           │   
  ├───────────────────────────────────────────────┼───────────────────────┼──────┼────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
  │ src/specify_cli/integrations/vibe/__init__.py │ specify init --ai     │ T1   │ Python CLI src → test the affected CLI command; vibe integration controls how .vibe/skills/*/SKILL.md files are scaffolded (adds user-invocable: true frontmatter via                  │   
  │                                               │ vibe                  │      │ post_process_skill_content)                                                                                                                                                            │ 
  ├───────────────────────────────────────────────┼───────────────────────┼──────┼────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤   
  │ src/specify_cli/integrations/vibe/__init__.py │ /speckit.specify      │ T2   │ Init/scaffolding change → mapping rule requires at minimum /speckit.specify to verify the scaffolded skills work end-to-end in a live agent session; depends on T1                     │
  ├───────────────────────────────────────────────┼───────────────────────┼──────┼────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤   
  │ tests/integrations/test_integration_vibe.py   │ specify init --ai     │ T1   │ Tests the same vibe integration code path; no additional slash-command surface beyond what the source file already maps to                                                             │ 
  │                                               │ vibe                  │      │                                                                                                                                                                                        │   
  └───────────────────────────────────────────────┴───────────────────────┴──────┴────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘ 
T1: specify init --ai vibe (CLI command) — The VibeIntegration.setup() and post_process_skill_content() changes affect every SKILL.md file written during init. Run uv run specify init <tmp-dir>/speckit-vibe-test --ai vibe --offline, then verify that every .vibe/skills/speckit-*/SKILL.md file contains user-invocable: true injected in its frontmatter block.                                                                                                                                                            
T2: /speckit.specify — Minimum slash-command test required for any init/scaffolding change. Open the T1-initialized project in Mistral Vibe and invoke /speckit.specify with a sample feature description. Confirm the command is user-invocable (Vibe surfaces it as a callable skill) and completes successfully, producing specs/<dir>/spec.md and the quality checklist. Requires T1.

• Tested with a sample project

AI Disclosure

• I did use AI assistance (describe below)
  This PR was drafted with the help of Claude. The code was then manually refined, largely by aligning it with the Claude integration. It also helped me understand the underlying logic and validate the implementation.

[Copilot]

Pull request overview

Migrates the Mistral Vibe integration from the legacy prompts-based Markdown command layout to the skills-based speckit-<name>/SKILL.md layout required by newer Vibe versions, and post-processes generated skills to add Vibe-specific frontmatter.

Changes:

• Switch VibeIntegration to subclass SkillsIntegration, updating config/registrar settings to .vibe/skills/speckit-<name>/SKILL.md.
• Add Vibe-specific post_process_skill_content() and a setup() post-pass to inject user-invocable: true.
• Update the Vibe integration test mixin from Markdown-based tests to skills-based tests.

Show a summary per file

File	Description
src/specify_cli/integrations/vibe/__init__.py	Converts Vibe integration to skills layout and injects user-invocable into generated SKILL.md files.
tests/integrations/test_integration_vibe.py	Updates integration test harness to validate Vibe as a SkillsIntegration.

Copilot's findings

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• Files reviewed: 2/2 changed files
• Comments generated: 2

[mnriem]

Please address Copilot feedback. If it is truly shareable code between all integrations using skills please pull it up into the SkillIngration

[Fango2007]

Done

[Copilot]

Copilot's findings

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• Files reviewed: 2/2 changed files
• Comments generated: 1

[mnriem]

@Fango2007 Please address Copilot feedback

[Copilot]

Copilot's findings

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• Files reviewed: 2/2 changed files
• Comments generated: 0 new

[mnriem]

Thank you!

[Fango2007]

Thank you.