docs: reflect tooling-package rename + Turbo boundaries enforcement

- Rename eslint-config → core-eslint, typescript-config → core-typescript
  in all docs (package map, AGENTS.md, overview.md, dependency-flow.md, etc.)
- Document the five-tag model (app, feature, core, core-composition,
  tooling) — refinement of ADR-006's three-tag mention
- Document core-trpc's core-composition tag (transitively reaches features
  through core-api's AppRouter type)
- Note Turborepo boundaries as a second enforcement layer alongside ESLint
- Add ADR-010 explaining the two-layer enforcement decision and
  five-tag refinement

Files updated:
- docs/architecture/overview.md: package map, enforcement layers, five-tag section
- docs/architecture/dependency-flow.md: boundary rules, enforcement strategy
- docs/architecture/vertical-feature-spec.md: package names, five-tag model
- AGENTS.md: package map, boundary rules, commands
- CLAUDE.md: tooling package names, quick-start command
- packages/core-eslint/AGENTS.md: tag clarification
- packages/core-typescript/AGENTS.md: tag clarification
- packages/core-api/AGENTS.md: core-composition tag
- packages/core-cms/AGENTS.md: core-composition tag
- packages/core-trpc/AGENTS.md: core-composition tag + rationale
- docs/decisions/adr-010-turbo-boundaries.md: new ADR

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

packages/core-api/AGENTS.md

@@ -1,5 +1,7 @@
 # AGENTS.md — core-api
 
+**Tag:** core-composition
+
 **Composition-only package** that aggregates feature tRPC routers into a single root `appRouter`. It does not define procedures; instead, it imports them from feature packages.
 
 ## Responsibilities

packages/core-cms/AGENTS.md

@@ -1,5 +1,7 @@
 # AGENTS.md — core-cms
 
+**Tag:** core-composition
+
 **Composition-only package** that aggregates feature Payload collections and globals into a single Payload config. It does not define its own collections; instead, it imports them from feature packages.
 
 ## Responsibilities

packages/core-eslint/AGENTS.md

@@ -1,6 +1,8 @@
-# AGENTS.md — eslint-config
+# AGENTS.md — core-eslint
 
-Shared ESLint 9 flat configs (rules, plugins, parser settings) consumed by all packages via `eslint.config.js`.
+**Tag:** tooling
+
+Shared ESLint 9 flat configs (rules, plugins, parser settings) consumed by all packages via `eslint.config.js`. Enforces boundary rules alongside Turborepo's `boundaries` feature (which validates the workspace dependency graph at build time).
 
 ## What it owns
 

packages/core-trpc/AGENTS.md

@@ -1,6 +1,8 @@
 # AGENTS.md — core-trpc
 
-Frontend tRPC platform providing the client and framework-specific providers (Next.js, TanStack). Bridges typed backend (`@repo/core-api`) to frontend applications.
+**Tag:** core-composition
+
+Frontend tRPC platform providing the client and framework-specific providers (Next.js, TanStack). Bridges typed backend (`@repo/core-api`) to frontend applications. Tagged `core-composition` (not `core`) because it transitively reaches features through `core-api`'s `AppRouter` type.
 
 ## Responsibilities
 

packages/core-typescript/AGENTS.md

@@ -1,4 +1,6 @@
-# AGENTS.md — typescript-config
+# AGENTS.md — core-typescript
+
+**Tag:** tooling
 
 Shared TypeScript base configs (`tsconfig.json` files) and Vitest base config, consumed by all packages.