Add hook matcher support to techpack schema

[bguidolim]

Summary

Add hookMatcher support to the techpack YAML schema, allowing pack authors to specify a regex matcher that filters when a hook fires. This maps directly to Claude Code's matcher field on HookGroup, which was already round-tripped in settings JSON but never populated from the pack pipeline.

Changes

• Add matcher: String? to HookRegistration struct and thread through Settings.addHookEntry(), YAML manifest decode/encode, sync composition (ConfiguratorSupport), export discovery (ConfigurationDiscovery), and YAML emission (ManifestBuilder)
• Add hookMatcher CodingKey with orphaned-metadata rejection (requires hookEvent, same as hookTimeout/hookAsync/hookStatusMessage)
• Add drift detection for matcher changes in addHookEntry() (compares groups[index].matcher on the HookGroup level)
• Update documentation in docs/techpack-schema.md, skills/techpack-creator/references/techpack-schema.md, and skills/techpack-creator/SKILL.md

Test plan

• swift test passes locally (963 tests, 7 new)
• swiftformat --lint . and swiftlint pass without violations

Checklist for engine changes

• Integration tests updated for new features (LifecycleIntegrationTests)
• Docs updated if behavior changed (docs/techpack-schema.md, skill references)