feat: Restructure Jan-Server Repository & Docs for Security/SEO Compliance

[locnguyen1986]

Description:
Migrate Jan’s website out of the main repository (to prevent phishing), reorganize docs, and establish a sustainable structure for Desktop/Server documentation. No new features or code changes allowed—only structural/organizational work.

Key Requirements from Your Input

Your Request	How It’s Addressed
Jan Repo organization	Split Jan UI/Jan Server into separate modules; remove legacy artifacts
Jan Docs vs. Jan Website	Deprecate website from Jan repo; move docs to dedicated repo (with SEO preservation)
OpenAPI/Swagger as checkpoint	Use this sprint to define only the doc structure (not full implementation)

---

Actionable Sub-Tasks

1. Repo Restructuring (Security First)

• Task: Split monorepo into:

  jan-server/  # Core API, RBAC, monitoring
  jan-ui/      # Desktop client (react)
  jan-docs/    # Public docs (OpenAPI + guides)

2. Docs Migration (SEO Preservation)

• Task: Move docs to jan-docs/ repo (public).
• Task: Add jan-website repo to README.md as a separate project.
  Docs live in jan-docs.”*

3. Doc Structure Definition (Milestone Only)

• Task: Create a draft OpenAPI spec structure (no actual Swagger implementation):
  • jan-docs/ will include:
    • /server (RBAC, monitoring, endpoints)
    • /desktop (client-specific flows)
    • /web ( web UI flows)
    • /migrating (for onboarding guides)

---