Refactor Nexus One AI product structure and roadmap

- Add Workstation as an additive standalone category, kept out of
  TIER_ORDER so it never enters the Server S/M/L/Max upgrade ladder
- Add Server S/M/L/Max commercial labels for existing starter/basic/pro/max
  tiers (slugs, license format, and APIs unchanged)
- Rename portal UI terminology: Connectors -> MCP & Enterprise Connectors,
  Audit Log -> Governance & Audit, Model Manager -> Model Catalog,
  Agent Builder -> Agent Studio, Workflow Automation -> Workflow Designer,
  Multimodal Chat -> AI Workspace
- Fix branding.js workflow.html tier-gating bug and entry.yml missing tier var
- Document 7-capability platform roadmap and Workstation/Server structure
  in README.md and docs/README.md
- Ignore __pycache__/*.pyc build artifacts

.gitignore

@@ -1,2 +1,4 @@
 *.iso
 .DS_Store
+__pycache__/
+*.pyc