chore: remove unused desktop app, cloud deployment infra, and monitoring stack

Deletes desktop/ (Electron wrapper), deployments/ (Helm/Kustomize/
Terraform/CI for cloud deploy), and monitoring/ (Prometheus + Grafana
stack) along with DESKTOP.md, DEPLOYMENT.md, docker-compose.full.yml,
their npm scripts, and every dangling reference across README,
ARCHITECTURE, INSTALL, SETUP, docs/, and the repeated per-file
MODULE_GUIDE "Observability" boilerplate comment. The GET /api/metrics
endpoint itself is untouched — it's the dashboard's own route, not
part of the removed monitoring stack.

.claude/skills/update-project-docs/references/doc-map.md

@@ -52,10 +52,10 @@ i18n architecture: **Supported languages** list, `supportedLngs`, the 15 namespa
 ## Tier 3 — situational
 
 - `.env.example` — every env var belongs here with a sane default + comment.
-- `INSTALL.md`, `SETUP.md`, `DEPLOYMENT.md`, `docs/DEPLOYMENT.md` — install/run/deploy commands.
+- `INSTALL.md`, `SETUP.md` — install/run commands.
 - `CLAUDE.md`, `AGENTS.md` — agent working guides; update when commands, file locations, or workflows change.
 - `docs/README.md` — docs index; add a link when a new `docs/*.md` is created.
-- `desktop/README.md`, `vscode-extension/README.md`, `statusline/README.md` — surface-specific; update only when that surface changes.
+- `vscode-extension/README.md`, `statusline/README.md` — surface-specific; update only when that surface changes.
 
 ## Consistency invariants