Add Python/FastAPI + PostgreSQL backend (Phase 1)

- server/: FastAPI app with SQLAlchemy models for sops, work_packages, comments
- Endpoints for SOP/WP upsert+list+get+delete and comment create+list;
  /api/feedback kept as an alias so the existing client keeps working
- Portable across engines (PostgreSQL prod, SQLite dev fallback)
- requirements.txt, .env.example, and server/README.md (Postgres + systemd)
- NGINX now proxies /api/ to the API (replaces the Power Automate hop;
  comments persist to SQL)
- Rewrite DEPLOYMENT.md for the API + database architecture
- Add .gitignore for venv/.env/sqlite

Phase 2 (wire the client apps to the API) is next.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/.env.example

@@ -0,0 +1,12 @@
+# Copy to .env (dev) or set these in the systemd unit (prod).
+
+# PostgreSQL connection (production). Format:
+#   postgresql+psycopg://USER:PASSWORD@HOST:5432/DBNAME
+DATABASE_URL=postgresql+psycopg://wpsuite:CHANGE_ME@localhost:5432/wpsuite
+
+# If DATABASE_URL is omitted entirely, the API falls back to a local SQLite
+# file (sqlite:///./wpsuite.db) — handy for trying it out without Postgres.
+
+# Only needed for CROSS-ORIGIN local development (comma-separated). In
+# production the site is same-origin via NGINX, so leave this unset.
+# CORS_ORIGINS=http://localhost:5500