docs(01): create phase 1 plans -- walking skeleton + portal shell

Three plans for Foundation & Portal Shell phase:
- 01-01: Monorepo scaffold, Docker Compose with 3-network segmentation, NestJS API, Next.js app, PostgreSQL
- 01-02: Design tokens (yellow #ffed00 primary), i18n (DE/EN), theme switching, responsive portal layout
- 01-03: Visual verification checkpoint for human approval

Includes SKELETON.md documenting architectural decisions for subsequent phases.

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

.planning/ROADMAP.md

@@ -32,7 +32,11 @@ Decimal phases appear between their surrounding integers in numeric order.
   3. User can toggle between light and dark theme and the preference persists
   4. User can switch between German and English interface language
   5. All UI strings are rendered through the i18n framework (no hardcoded text)
-**Plans**: TBD
+**Plans**: 3 plans
+Plans:
+- [ ] 01-01-PLAN.md -- Walking Skeleton: Monorepo + Docker Compose stack with NestJS, Next.js, PostgreSQL, Traefik
+- [ ] 01-02-PLAN.md -- Portal Shell: Design tokens, i18n (DE/EN), theme switching, responsive layout with header + sidebar
+- [ ] 01-03-PLAN.md -- Visual Verification: Human confirms portal appearance and interactions
 **UI hint**: yes
 
 ### Phase 2: Authentication & Multi-Tenancy
@@ -103,11 +107,11 @@ Decimal phases appear between their surrounding integers in numeric order.
 ## Progress
 
 **Execution Order:**
-Phases execute in numeric order: 1 → 2 → 3 → 4 → 5 → 6
+Phases execute in numeric order: 1 -> 2 -> 3 -> 4 -> 5 -> 6
 
 | Phase | Plans Complete | Status | Completed |
 |-------|----------------|--------|-----------|
-| 1. Foundation & Portal Shell | 0/TBD | Not started | - |
+| 1. Foundation & Portal Shell | 0/3 | Planned | - |
 | 2. Authentication & Multi-Tenancy | 0/TBD | Not started | - |
 | 3. Module System & Domaincheck | 0/TBD | Not started | - |
 | 4. Marketplace & Portal Navigation | 0/TBD | Not started | - |