chore: initialize repository with project rules, docs, and phase-1 ADRs

Set up the foundation for the adastra-portal project:

- CLAUDE.md captures durable project rules (quality bar, security/perf/a11y
  as first-class, language, commit conventions, ADR proactivity).
- docs/ and decisions/ scaffolding with maintained indexes (docs/README.md
  and decisions/README.md), MADR 4.0.0 template, and tag vocabulary.
- Phase-1 ADRs (0001-0006) lock structural choices: ADR usage, Nx monorepo
  with the apps preset, naming convention (adastra-portal / portal-shell /
  portal-bff), Angular CSR/zoneless/Signals/Vitest, NestJS over Express,
  PostgreSQL with Prisma.
- docs/setup/ guides translated to English.
- .gitignore covers Node/Nx artifacts and the personal notes/ scratchpad.

The Nx workspace itself is not yet bootstrapped; that step is gated on a
revised setup guide aligned with the ADRs.

docs/setup/02-dev-web-stack.md

@@ -0,0 +1,100 @@
+# ⚙️ Web dev stack (Node + pnpm + tooling)
+
+## Goal
+
+Install a modern, reproducible stack.
+
+---
+
+## 1) Install Node via nvm
+
+```bash
+curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/master/install.sh | bash
+source ~/.zshrc
+```
+
+Install Node LTS:
+
+```bash
+nvm install --lts
+nvm alias default 'lts/*'
+```
+
+---
+
+## 2) Activate pnpm
+
+```bash
+corepack enable
+corepack prepare pnpm@latest --activate
+pnpm setup
+exec zsh
+```
+
+---
+
+## 3) Working tree
+
+Create a dev folder:
+
+```bash
+mkdir -p ~/dev
+cd ~/dev
+```
+
+⚠️ Do not work inside `/mnt/c` (slow I/O).
+
+---
+
+## 4) Conventions
+
+* ❌ No global Angular install
+* ✅ Use `pnpm dlx`
+* ✅ Versions pinned per project
+
+---
+
+## 5) Useful commands
+
+```bash
+pnpm install
+pnpm run dev
+pnpm run build
+pnpm run test
+```
+
+---
+
+## 6) VS Code
+
+Recommended extensions:
+
+* WSL
+* Angular Language Service
+* ESLint
+* Prettier
+* GitLens
+
+---
+
+## 7) Docker
+
+Install Docker Desktop (Windows).
+
+Enable:
+
+* Settings → WSL Integration → Debian
+
+Test:
+
+```bash
+docker ps
+```
+
+---
+
+## Result
+
+* Stable environment
+* Clean version management
+* Team-compatible