remove(console): drop the standalone Compose panel - #94

…y panel

Brett: hard to understand how to use the Compose panel, let's remove it
first — then also remove the MANAGING oab panel.

Compose: it was always a duplicate surface — the ADR itself flagged this at
slice 6 ("where template/overlay authoring moves to once this standing
section goes away isn't decided"). The `[+ New fleet]`/`[+ Add instance]`
deploy panel (`deploy.ts`) already reaches the identical compose→preview→
deploy engine as an action, with its own template/overlay pickers, preview,
and deploy-to-ECS step — removing the standalone one loses no capability,
just the redundant standing "Library" JSON-authoring surface.

Identity: `#identity`'s content (which AWS principal is managing this
cluster) is gone along with `.mgmt-combo` (the shared box PR #93 built for
it) — `#remote` is back to its own full-radius box, standalone.

## What
- Dropped `#compose-standalone` + its init (`initComposeTab`, `compose.ts`)
  and the now-Fleets-screen-only `updateScreen()` toggle for it. Trimmed
  `compose.ts` to the pure helpers `deploy.ts` still imports
  (`renderPreviewHtml`, `libraryNames`, the `Library`/`BundlePreview` types);
  `compose.test.ts` already only covered those, so no test changes there.
- Dropped `#identity`, `identityHtml`/`renderIdentity`/`kindBadge`
  (render.ts), and every `refreshIdentity()` call site (main.ts). Kept
  `field()` — shared with `agentConsoleHeaderHtml`'s `.ac-fields` — and
  `Source.runtimeContext()`/`RuntimeContext`/its fixture (backend contract,
  not UI surface — same call as leaving `Source.fsList` alone when the Files
  panel came out).
- CSS: removed both panels' exclusive rules; kept everything still shared
  with `deploy.ts`'s compose step or the agent console header.

## Verification
- `tsc --noEmit` — clean
- `vitest run` — 97/97 passing
- `vite build` — clean; `dist/index.html` 17.27kB → 12.34kB
- Playwright: confirmed both panels are gone from the DOM, `[+ New fleet]`
  still reaches Compose normally, and the agent console header (which reuses
  `field()`) still renders.

🤖 Generated by Orca ('ecs-claude').