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/create-epics/SKILL.md

@@ -1,7 +1,7 @@
 ---
 name: create-epics
 description: "Translate approved GDDs + architecture into epics — one epic per architectural module. Defines scope, governing ADRs, engine risk, and untraced requirements. Does NOT break into stories — run /create-stories [epic-slug] after each epic is created."
-argument-hint: "[system-name | layer: foundation|core|feature|presentation | all]"
+argument-hint: "[system-name | layer: foundation|core|feature|presentation | all] [--review full|lean|solo]"
 user-invocable: true
 allowed-tools: Read, Glob, Grep, Write
 context: fork
@@ -28,6 +28,9 @@ will have changed.
 
 ## 1. Parse Arguments
 
+Extract `--review [full|lean|solo]` if present and store as the review mode
+override for this run (see `.claude/docs/director-gates.md`).
+
 **Modes:**
 - `/create-epics all` — process all systems in layer order
 - `/create-epics layer: foundation` — Foundation layer only