feat(skills): single-source skill system with markdown SKILL.md + include directive

Skills move out of packages/core/src/application/assistant/skills/*/skill.ts
(TS string constants) into apps/skills/<id>/SKILL.md (Agent Skills spec format
— YAML frontmatter + markdown body). One directory, one loader, one place to
look at every skill the agent can load.

Key change vs the old dev system: a `{{include:<skill-id>}}` directive lets one
skill transclude another. This removes the parallel TS constant for the
knowledge-note style guide — it now lives at apps/skills/knowledge-note-style/
(hidden from catalog) and is pulled into doc-collab + the live-note and
background-task agents via the resolver instead of via a TS import.

Infrastructure:
- packages/core/src/skills/ — types, skill-md-parser, FS-backed official repo,
  SkillResolver with recursive {{include:<id>}} expansion + cycle detection
- packages/shared/src/skill.ts — SkillFrontmatter, SkillCatalogEntry,
  ResolvedSkill schemas
- DI: officialSkillsRepo + skillResolver registered; registerSkillsDir helper
  wires the path before any consumer resolves
- IPC: skills:list / skills:get (read-only) for the Settings UI
- Main: resolveSkillsDir picks Resources/skills (packaged) or repo apps/skills
  (dev). forge.config.cjs ships apps/skills/ as extraResource.

Consumer refactor:
- buildCopilotInstructions: catalog markdown built from resolver.getCatalog()
- builtin-tools: loadSkill uses resolver, new listSkills tool
- background-tasks/agent + live-note/agent: now async builders that load
  the knowledge-note-style skill content via resolver
- runtime.loadAgent: awaits the now-async builders
- Deleted: assistant/skills/ directory, knowledge-note-style.ts

UI:
- New SkillsSettings component (read-only list + detail view) wired into
  Settings dialog as the "Skills" tab.

apps/skills/composio-integration/SKILL.md

@@ -0,0 +1,131 @@
+---
+name: composio-integration
+description: >-
+  Interact with third-party services (Gmail, GitHub, Slack, LinkedIn, Notion, Jira, Google Sheets, etc.) via Composio. Search, connect, and execute tools.
+metadata:
+  title: "Composio Integration"
+---
+
+# Composio Integration
+
+**Load this skill** when the user asks to interact with ANY third-party service — email, GitHub, Slack, LinkedIn, Notion, Jira, Google Sheets, calendar, etc. This skill provides the complete workflow for discovering, connecting, and executing Composio tools.
+
+## Available Tools
+
+| Tool | Purpose |
+|------|---------|
+| **composio-list-toolkits** | List all available integrations and their connection status |
+| **composio-search-tools** | Search for tools by use case; returns slugs and input schemas |
+| **composio-execute-tool** | Execute a tool by slug with parameters |
+| **composio-connect-toolkit** | Connect a service via OAuth (opens browser) |
+
+## Toolkit Slugs (exact values for toolkitSlug parameter)
+
+| Service | Slug |
+|---------|------|
+| Gmail | `gmail` |
+| Google Calendar | `googlecalendar` |
+| Google Sheets | `googlesheets` |
+| Google Docs | `googledocs` |
+| Google Drive | `googledrive` |
+| Slack | `slack` |
+| GitHub | `github` |
+| Notion | `notion` |
+| Linear | `linear` |
+| Jira | `jira` |
+| Asana | `asana` |
+| Trello | `trello` |
+| HubSpot | `hubspot` |
+| Salesforce | `salesforce` |
+| LinkedIn | `linkedin` |
+| X (Twitter) | `twitter` |
+| Reddit | `reddit` |
+| Dropbox | `dropbox` |
+| OneDrive | `onedrive` |
+| Microsoft Outlook | `microsoft_outlook` |
+| Microsoft Teams | `microsoft_teams` |
+| Calendly | `calendly` |
+| Cal.com | `cal` |
+| Intercom | `intercom` |
+| Zendesk | `zendesk` |
+| Airtable | `airtable` |
+
+**IMPORTANT:** Always use these exact slugs. Do NOT guess — e.g., Google Sheets is `googlesheets` (no underscore), not `google_sheets`.
+
+## Critical: Check First, Connect Second
+
+**BEFORE calling composio-connect-toolkit, ALWAYS check if the service is already connected.** The system prompt includes a "Currently connected" list. If the service is there, skip connecting and go straight to search + execute.
+
+**Flow:**
+1. Check if the service is in the "Currently connected" list (in the system prompt above)
+2. If **connected** → go directly to step 4
+3. If **NOT connected** → call `composio-connect-toolkit` once, wait for user to authenticate, then continue
+4. Call `composio-search-tools` with SHORT keyword queries
+5. Read the `inputSchema` from results — note `required` fields
+6. Call `composio-execute-tool` with slug, toolkit, and all required arguments
+
+**NEVER call composio-connect-toolkit for a service that's already connected.** This creates duplicate connect cards in the UI.
+
+## Search Query Tips
+
+Use **short keyword queries**, not full sentences:
+
+| ✅ Good | ❌ Bad |
+|---------|--------|
+| "list issues" | "get all open issues for a GitHub repository" |
+| "send email" | "send an email to someone using Gmail" |
+| "get profile" | "fetch the authenticated user's profile details" |
+| "create spreadsheet" | "create a new Google Sheets spreadsheet with data" |
+
+If the first search returns 0 results, try a different short query (e.g., "issues" instead of "list issues").
+
+## Passing Arguments
+
+**ALWAYS include the `arguments` field** when calling `composio-execute-tool`, even if the tool has no required parameters.
+
+- Read the `inputSchema` from search results carefully
+- Extract user-provided values into the correct fields (e.g., "rowboatlabs/rowboat" → `owner: "rowboatlabs", repo: "rowboat"`)
+- For tools with empty `properties: {}`, pass `arguments: {}`
+- For tools with required fields, pass all of them
+
+### Example: GitHub Issues
+
+User says: "Get me the open issues on rowboatlabs/rowboat"
+
+1. `composio-search-tools({ query: "list issues", toolkitSlug: "github" })`
+   → finds `GITHUB_ISSUES_LIST_FOR_REPO` with required: ["owner", "repo"]
+2. `composio-execute-tool({ toolSlug: "GITHUB_ISSUES_LIST_FOR_REPO", toolkitSlug: "github", arguments: { owner: "rowboatlabs", repo: "rowboat", state: "open", per_page: 100 } })`
+
+### Example: Gmail Fetch
+
+User says: "What's my latest email?"
+
+1. `composio-search-tools({ query: "fetch emails", toolkitSlug: "gmail" })`
+   → finds `GMAIL_FETCH_EMAILS`
+2. `composio-execute-tool({ toolSlug: "GMAIL_FETCH_EMAILS", toolkitSlug: "gmail", arguments: { user_id: "me", max_results: 5 } })`
+
+### Example: LinkedIn Profile (no-arg tool)
+
+User says: "Get my LinkedIn profile"
+
+1. `composio-search-tools({ query: "get profile", toolkitSlug: "linkedin" })`
+   → finds `LINKEDIN_GET_MY_INFO` with properties: {}
+2. `composio-execute-tool({ toolSlug: "LINKEDIN_GET_MY_INFO", toolkitSlug: "linkedin", arguments: {} })`
+
+## Error Recovery
+
+- **If a tool call fails** (missing fields, 500 error): Fix the arguments and retry IMMEDIATELY. Do NOT stop and narrate the error to the user.
+- **If search returns 0 results**: Try a different short query. If still 0, the tool may not exist for that service.
+- **If a tool requires connection**: Call `composio-connect-toolkit` once, then retry after connection.
+
+## Multi-Part Requests
+
+When the user says "connect X and then do Y" — complete BOTH parts in one turn:
+1. If X is already connected (check the connected list), skip to Y immediately
+2. If X needs connecting, connect it, then proceed to Y after authentication
+
+## Confirmation Rules
+
+- **Read-only actions** (fetch, list, get, search): Execute without asking
+- **Mutating actions** (send email, create issue, post, delete): Show the user what you're about to do and confirm before executing
+- **Connecting a toolkit**: Always safe — just do it when needed