feat: add source-driven skill publishing pipeline

[ksamaschke]

Summary

• add a unified skill publishing pipeline across installer core, CLI, and dashboard
• support source-configured publish flows (direct-push, branch-only, branch-pr) plus official contribution flow and strict validation
• add advanced per-run publish overrides (mode/base branch), official-source guardrails, and docs/schema updates

Changes

• implemented new core publish module with bundle copy/validation, provider detection, publish execution, and official contribution branch/PR handling
• extended source model/types/schemas/catalog handling and recursive resource support
• expanded CLI commands for skill validate/publish/contribute and source publish settings, plus local ica serve flow improvements already present in staged work
• redesigned dashboard skill publishing UX with overlay-based target/advanced settings, quick publish and folder picker flows, and source setting controls
• added/updated installer tests for publish pipeline, dashboard publish UX, source migration, claude hook matcher behavior, and serve CLI behavior
• fixed flaky pre-commit test gate by cleaning stale compiled dist/tests artifacts before build:quick

Test Plan

• npm test
• npm run build
• npm run build:quick && node --test dist/tests/installer/dashboard-skill-publish-ux.test.js dist/tests/installer/skill-publish.test.js

Breaking Changes

• none intended