feat: add 5 lifecycle extensions to community catalog (#2049)

* feat: add 5 gstack-inspired lifecycle commands (critique, review, qa, ship, retro)

Add 5 new core command templates inspired by Garry Tan's GStack to complete
the spec-driven development lifecycle:

- /speckit.critique: Dual-lens product + engineering review before implementation
- /speckit.review: Staff-level code review (correctness, security, performance)
- /speckit.qa: Systematic QA testing (browser-driven and CLI modes)
- /speckit.ship: Release automation (pre-flight, changelog, CI, PR creation)
- /speckit.retro: Sprint retrospective with metrics and improvement suggestions

Each command includes:
- Command template in templates/commands/
- Output report template in templates/
- Extension hook support (before_*/after_*)
- YAML frontmatter with prerequisite scripts

Updated README.md workflow from 6 to 11 steps and added CHANGELOG entry.

Co-authored-by: Copilot <[email protected]>

* Revert "feat: add 5 gstack-inspired lifecycle commands (critique, review, qa, ship, retro)"

This reverts commit 6eb15a7a3ee201d1e3743e5f0d92173b1503f9e6.

* feat: add 5 lifecycle extensions to community catalog

Add the following community extensions:
- staff-review: Staff-engineer-level code review
- qa: Systematic QA testing with browser/CLI validation
- ship: Release engineering automation
- retro: Sprint retrospective with metrics
- critique: Dual-lens spec and plan critique

Each extension is hosted in its own repository under arunt14/
with v1.0.0 releases available.

* fix: resolve mojibake encoding, sort keys, rename retro extension

- Fix double-encoded em dashes and arrows in catalog.community.json
- Sort extension entries alphabetically by key
- Rename 'Retrospective Extension' to 'Retro Extension' to avoid
  name collision with existing 'retrospective' extension

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Co-authored-by: Copilot <[email protected]>