Merge branch 'main' into garrytan/enable-plan-tune (catch up to v1.48.0.0)

Brings in v1.48.0.0 (AskUserQuestion 5+-option split rule + runtime
AUTO_DECIDE carve-out).

Conflict resolutions:
- VERSION + package.json: keep 1.49.0.0 (still queue-ahead of main's 1.48.0.0)
- CHANGELOG.md: insert main's 1.48.0.0 entry below ours, keep reverse-chronological order
- Regenerated all SKILL.md files via gen:skill-docs to inherit the new
  'Handling 5+ options — split, never drop' preamble subsection
- Refreshed claude/codex/factory ship golden fixtures

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

docs/skills.md

@@ -5,6 +5,7 @@ Detailed guides for every gstack skill — philosophy, workflow, and examples.
 | Skill | Your specialist | What they do |
 |-------|----------------|--------------|
 | [`/office-hours`](#office-hours) | **YC Office Hours** | Start here. Six forcing questions that reframe your product before you write code. Pushes back on your framing, challenges premises, generates implementation alternatives. Design doc feeds into every downstream skill. |
+| [`/spec`](#spec) | **Spec Author** | Turn vague intent into a precise, executable spec in five phases. Backlog-ready output that downstream skills can pick up. Optional agent spawn at the end. |
 | [`/plan-ceo-review`](#plan-ceo-review) | **CEO / Founder** | Rethink the problem. Find the 10-star product hiding inside the request. Four modes: Expansion, Selective Expansion, Hold Scope, Reduction. |
 | [`/plan-eng-review`](#plan-eng-review) | **Eng Manager** | Lock in architecture, data flow, diagrams, edge cases, and tests. Forces hidden assumptions into the open. |
 | [`/plan-design-review`](#plan-design-review) | **Senior Designer** | Interactive plan-mode design review. Rates each dimension 0-10, explains what a 10 looks like, fixes the plan. Works in plan mode. |