docs: surface turbo gen feature in AGENTS.md and CLAUDE.md

Wires the existing turbo gen feature generator into AGENTS.md (Adding
a Feature section, Key Commands, Specification & Guides) and
CLAUDE.md (Quick Start, Read First). Adds a fast-path callout at the
top of the manual walkthrough in docs/guides/adding-a-feature.md
pointing at scaffolding-a-feature.md.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -3,12 +3,13 @@
 ## Quick Start
 
 ```bash
-pnpm install          # Install all dependencies
-pnpm dev              # Start all dev servers
-pnpm build            # Build all packages
-pnpm test             # Run all tests
-pnpm turbo boundaries # Validate workspace dependency graph
-docker compose up -d  # Start PostgreSQL
+pnpm install           # Install all dependencies
+pnpm dev               # Start all dev servers
+pnpm build             # Build all packages
+pnpm test              # Run all tests
+pnpm turbo boundaries  # Validate workspace dependency graph
+pnpm turbo gen feature # Scaffold a new feature package (see docs/guides/scaffolding-a-feature.md)
+docker compose up -d   # Start PostgreSQL
 ```
 
 ## TDD
@@ -31,7 +32,8 @@ Turborepo + pnpm monorepo organized by vertical features. Each feature (`auth`,
 - `AGENTS.md` — Package map, boundary rules, per-package conventions
 - `docs/architecture/overview.md` — High-level architecture and package responsibilities
 - `docs/architecture/vertical-feature-spec.md` — Design spec with rationale and decision log
-- `docs/guides/adding-a-feature.md` — End-to-end new feature walkthrough
+- `docs/guides/scaffolding-a-feature.md` — `turbo gen feature` reference (fast path; prefer this over the manual walkthrough)
+- `docs/guides/adding-a-feature.md` — End-to-end new feature walkthrough (manual path; for cases the generator's Phase-1 scope doesn't cover)
 
 ## Key Conventions