docs-08: Write Bundle Overview Pages For All 6 Official Bundles

[djm81]

Summary

Write 6 new bundle overview pages (backlog, project, codebase, spec, govern, code-review) listing all commands, prerequisites, quick examples, and links to deep guides.

OpenSpec Change

• Change folder: openspec/changes/docs-08-bundle-overview-pages/
• Priority: P1
• Depends on: docs-06-modules-site-ia-restructure

Source Plan

specfact-cli-internal/docs/internal/implementation/2026-03-23-docs-refactoring-beginner-to-enterprise-plan.md