feat: implement local registry loader (packages/registry)

[Copilot]

The CLI had no central index for discovering available action packs, skills, and packs. Per the PRD, a packages/registry/ directory with JSON index files is the canonical local source for this metadata.

Changes

New package: @profullstack/sh1pt-registry

• actions.json / skills.json / packs.json — index files listing all built-in entries with name, publisher, version, description, trustLevel, category, and path fields
• src/index.ts — exports loadActionsRegistry(), loadSkillsRegistry(), loadPacksRegistry() with descriptive error wrapping on I/O and parse failures

const actions = await loadActionsRegistry();
// [{ name: 'vu1nz-scan', trustLevel: 'verified', category: 'security', path: 'packages/actions/vu1nz-scan/sh1pt.actionpack.yaml', ... }, ...]

CLI integration

• packages/cli/src/lib/registry.ts — thin re-export so CLI commands import from a stable local path
• packages/cli/package.json — adds @profullstack/sh1pt-registry: workspace:^

Initial registry entries

Type	Entries
actions	vu1nz-scan, node-pnpm-ci, node-pnpm-test
skills	modern-web
packs	(empty, schema ready)

[alwaysmeticulous]

Meticulous was unable to execute a test run for this PR because the most recent commit is associated with multiple PRs. To execute a test run, please try pushing up a new commit that is only associated with this PR.

_{Last updated for commit f505900. This comment will update as new commits are pushed.}