### Summary
This PR refactors the playbook layout to reduce duplication and make host intent clearer (servers vs workstations), splits monitoring by host type, and restores full Zsh setup for developers while keeping servers aliases-only.
### Key changes
- **New playbooks**
- `playbooks/servers.yml`: baseline for server-class hosts (no desktop apps)
- `playbooks/workstations.yml`: baseline for dev/desktop/local + **desktop apps only on `desktop` group**
- **Monitoring split**
- `roles/monitoring_server`: server monitoring + intrusion prevention (includes `fail2ban`, sysstat)
- `roles/monitoring_desktop`: desktop-oriented monitoring tooling
- Updated playbooks to use the correct monitoring role per host type
- **Shell role: server-safe + developer-friendly**
- `roles/shell` now supports two modes:
- `shell_mode: minimal` (default): aliases-only, does not overwrite `.zshrc`
- `shell_mode: full`: installs Oh My Zsh + Powerlevel10k + plugins and deploys a managed `.zshrc`
- `playbooks/development.yml` and `playbooks/workstations.yml` use `shell_mode: full`
- `playbooks/servers.yml` remains **aliases-only**
- **Applications**
- Applications role runs only on `desktop` group (via `workstations.yml`)
- Removed Brave installs/repo management
- Added **CopyQ** to desktop apps (`applications_desktop_packages`)
- **Docs + architecture**
- Added canonical doc tree under `project-docs/` (overview/architecture/standards/workflow/decisions)
- Consolidated architecture docs: `docs/reference/architecture.md` is now a pointer to `project-docs/architecture.md`
- Fixed broken doc links by adding the missing referenced pages under `docs/`
### Behavior changes (important)
- Desktop GUI apps install **only** on the `desktop` inventory group (not on servers, not on dev VMs unless they are in `desktop`).
- Dev/workstation Zsh is now provisioned in **full mode** (managed `.zshrc` + p10k).
### How to test (local CI parity)
```bash
make test
npm test
```
Optional dry runs (interactive sudo may be required):
```bash
make check
make check-local
```
### Rollout guidance
- Apply to a single host first:
- Workstations: `make workstations HOST=<devhost>`
- Servers: `make servers HOST=<serverhost>`
- Then expand to group runs.
Reviewed-on: #4
