feat(atlas): per-job CI status + build-injected version in the UI

Phase C: the CI stage now shows the latest run's per-JOB status (Lint/Test,
Build, Deploy, …), each coloured by outcome, from the Gitea /actions/tasks
per-job entries — replacing the static cd.yml job-id list when live.
LatestRunJobs/RunNodes + RunSummary.State aggregate, all test-first.

Version: injected at build via -ldflags from `git describe --tags` (CI checkout
now fetch-depth:0 + --build-arg), served in /api/atlas.json, shown in the header.
No more hand-maintained version label drifting from the git tag.

Verified: build/vet/lint(0)/test green; version ldflag served correctly.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/atlas/model.go

@@ -35,6 +35,7 @@ type Stage struct {
 
 // Atlas is the full data model the frontend renders.
 type Atlas struct {
+	Version   string  `json:"version,omitempty"`
 	Substrate []Host  `json:"substrate"`
 	NS        string  `json:"ns,omitempty"`
 	Stages    []Stage `json:"stages"`