13 commits since v0.5.0 (minor bump)

- fix(ui): ICD-aware empty state in Build Output panel
- feat(icd): drift detector + log retention bump
- feat(icd): retry chain + Discord alert + log mutex for revalidation
- feat(F144 P3+): source-fetch closes gap from original P3 commit
- fix(api): cms.ts now honors withSiteContext override
- feat(admin): /admin/switch/<slug> route + F146 plan for URL-based site routing