feat(atlas): surface the user's own Gitea repos on stage 05 (#10)

Adds the repos panel from #4's "Not yet shipped" list, following the shipped
issues slice (b2761a4) structurally rather than inventing a second approach:

- internal/atlas/repos.go — RepoNodes(), a pure parser over an already-decoded
  /user/repos response. Archived repos are dropped: the atlas shows where work
  happens, and an archived repo is by definition somewhere it does not.
- internal/gitea/client.go — MyRepos(), same PAT and same contract as MyIssues:
  errors when GITEA_TOKEN is unset so the caller skips the overlay rather than
  issuing an unauthenticated request. That unset path is the one running in
  prod today (#4), so it is tested, not assumed.
- internal/web/handler.go — wired into liveOverlay().

Stage 05 is the right home — repos are what the execution stage acts on — but
#11 had just claimed its `generate` key for stuck-badges, and a stage could
only name one source. So `generate` now accepts either spelling:

    "generate": "ci-jobs"
    "generate": ["stuck-badges", "gitea-repos"]

The bare string stays valid and marshals back as a bare string, so no authored
stage is rewritten and the frontend contract is unchanged. Stages 04 and 08
already share stuck-badges between them; this is the same growth one level in.

The overlay merge also moves out of the handler into atlas.PrependGenerated,
which is unit-testable where the inline loop was not — it sat behind a network
call. It covers the issues path too, and fixes a latent aliasing bug there: the
old `append(liveNodes, authored...)` wrote into the live slice's backing array,
so two stages sharing a key would corrupt each other. That shape is no longer
hypothetical now that stuck-badges spans three stages.

Verified end-to-end both ways: without GITEA_TOKEN the atlas returns 200 with
stage 05's authored nodes intact; with a real token stage 05 serves both
overlays at once — stuck badges, then eight live repos, then the authored
nodes — and a repo with no language emits one tag rather than an empty pill.

task check green (golangci-lint 0 issues, vet, -race).

Closes #10.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

internal/atlas/atlas.json

@@ -34,7 +34,7 @@
       {"t":"Human triggers execution","plain_t":"The go button","plain":"A person confirms the plan and its risk level, then releases the work — nothing runs until they do.","cls":"gateway","pill":"var(--amber)","d":"Ratify proposed-plan + risk tier, then dispatch.","gate":true},
       {"t":"Session-Dispatch bridge","plain_t":"Hand-off to agents","plain":"The approval flips a switch that hands the signed work order over to the agents to start execution.","cls":"bridge","pill":"var(--blue)","d":"claude.ai MCP → gitea:workflow_run_trigger → cad-dispatch.yml → agentsquad. The final design→execution bridge.","tags":["workflow_dispatch"]}
     ]},
-    {"no":"STAGE 05","short":"Build","cls":"exec","title":"Execute · agentsquad + dispatch","plain_title":"Agents do the work","plain":"AI agents actually build the thing — one writes, a second independent one reviews it to avoid marking its own homework — and every step is logged for the audit trail. Two execution paths run today: agentsquad for orchestrated multi-agent jobs, and dispatch for headless single-issue work.","path":"koala · agentsquad-serve + dispatch CronJob","generate":"stuck-badges",
+    {"no":"STAGE 05","short":"Build","cls":"exec","title":"Execute · agentsquad + dispatch","plain_title":"Agents do the work","plain":"AI agents actually build the thing — one writes, a second independent one reviews it to avoid marking its own homework — and every step is logged for the audit trail. Two execution paths run today: agentsquad for orchestrated multi-agent jobs, and dispatch for headless single-issue work.","path":"koala · agentsquad-serve + dispatch CronJob","generate":["stuck-badges","gitea-repos"],
      "trans_label":"Change proposed","trans":"Advances when the agents finish and open a proposed change (a PR) with its audit log attached. Until there's a concrete change to test, nothing moves.","nodes":[
       {"t":"Task API","plain_t":"Start a job","plain":"A request kicks off a job and hands back an id you can poll for progress.","pill":"var(--coral)","d":"POST /tasks → job id · GET /tasks/{id}. taskqueue + serve (v0.12+).","tags":["single agentsquad.yaml"]},
       {"t":"Executor + reviewer loop","plain_t":"Build + independent review","plain":"One agent does the work; a second, independent agent on a different model reviews it — so nothing marks its own homework.","cls":"win","pill":"var(--coral)","d":"ADK Go + LiteLLM. Frontier models (local qwen spirals). Reviewer on distinct tier — echo-chamber prevention.","risk":true},