Add gate intensity modes: full, lean, and solo review control

Adds a --review flag to all 13 gate-using skills and a global
production/review-mode.txt config (set during /start). Full runs all
director gates, lean skips per-skill gates but keeps phase gates, solo
skips all directors. Documents modes in director-gates.md, WORKFLOW-GUIDE.md,
and README.md.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/skills/start/SKILL.md

@@ -3,12 +3,12 @@ name: start
 description: "First-time onboarding — asks where you are, then guides you to the right workflow. No assumptions."
 argument-hint: "[no arguments]"
 user-invocable: true
-allowed-tools: Read, Glob, Grep, AskUserQuestion
+allowed-tools: Read, Glob, Grep, Write, AskUserQuestion
 ---
 
 # Guided Onboarding
 
-This skill is read-only — it reports findings but writes no files.
+This skill writes one file: `production/review-mode.txt` (review mode config set in Phase 3b).
 
 This skill is the entry point for new users. It does NOT assume you have a game idea, an engine preference, or any prior experience. It asks first, then routes you to the right workflow.
 
@@ -145,6 +145,31 @@ The user needs creative exploration before anything else.
 
 ---
 
+## Phase 3b: Set Review Mode
+
+Check if `production/review-mode.txt` already exists.
+
+**If it exists**: Read it and show the current mode — "Review mode is set to `[current]`." — then proceed to Phase 4. Do not ask again.
+
+**If it does not exist**: Use `AskUserQuestion`:
+
+- **Prompt**: "One setup choice: how much design review would you want as you work through the workflow?"
+- **Options**:
+  - `Full (recommended)` — Director specialists review at each key workflow step. Best for new projects or when you want structured feedback on your decisions.
+  - `Lean` — Directors only at phase gate transitions (/gate-check). Skips per-skill reviews. For experienced users who trust their own design work.
+  - `Solo` — No director reviews at all. Maximum speed. Best for game jams, prototypes, or if the reviews feel like overhead.
+
+Write the choice to `production/review-mode.txt` immediately after the user
+selects — no separate "May I write?" needed, as the write is a direct
+consequence of the selection:
+- `Full (recommended)` → write `full`
+- `Lean` → write `lean`
+- `Solo` → write `solo`
+
+Create the `production/` directory if it does not exist.
+
+---
+
 ## Phase 4: Confirm Before Proceeding
 
 After presenting the recommended path, use `AskUserQuestion` to ask the user which step they'd like to take first. Never auto-run the next skill.
@@ -168,7 +193,7 @@ Verdict: **COMPLETE** — user oriented and handed off to next step.
 
 - **User picks D but project is empty**: Gently redirect — "It looks like the project is a fresh template with no artifacts yet. Would Path A or B be a better fit?"
 - **User picks A but project has code**: Mention what you found — "I noticed there's already code in `src/`. Did you mean to pick D (existing work)?"
-- **User is returning (engine configured, concept exists)**: Skip onboarding entirely — "It looks like you're already set up! Your engine is [X] and you have a game concept at `design/gdd/game-concept.md`. Want to pick up where you left off? Try `/sprint-plan` or just tell me what you'd like to work on."
+- **User is returning (engine configured, concept exists)**: Skip onboarding entirely — "It looks like you're already set up! Your engine is [X] and you have a game concept at `design/gdd/game-concept.md`. Review mode: `[read from production/review-mode.txt, or 'full (default)' if missing]`. Want to pick up where you left off? Try `/sprint-plan` or just tell me what you'd like to work on."
 - **User doesn't fit any option**: Let them describe their situation in their own words and adapt.
 
 ---