add workflow page — dev-flow centerpiece

New docs/workflow.md covering how we actually work day to day:
- why git / why WSL2 (our reasons, links out for generic install)
- signing up on our Gitea (self-serve register, SSH + deploy-key model)
- our git vs public git: per-repo identity, signed commits, develop->main
- our-flavored git basics (everyday loop, commit small/often, gl graph)
- the dev workflow: plan-in-chat / build-in-Claude-Code, tmux split,
  claudedo voice control, the .claude/ project convention, AI-assist
  habits (git diff | clip.exe)
- recommended setup (WSL + VS Code + Claude Code, pyenv, flake8)
- handy .zshrc/.bashrc snippets with prose on the high-value ones

Claude-first but soft: any AI works, we recommend Claude, and the
.claude/ structure is built on that preference. Sanitized with
placeholders throughout. Nav: Home / Libraries / Standards / Workflow /
Deploy; landing card grid updated.

Verified: mkdocs build --strict clean.
Signed-off-by: disqualifier <dev@disqualifier.me>

mkdocs.yml

@@ -59,4 +59,5 @@ nav:
   - Home: index.md
   - Libraries: libraries.md
   - Standards: standards.md
+  - Workflow: workflow.md
   - Deploy: deploy.md