feat(agent): agent workspace with vertical rail and settings navigator (CLEAN-36)

[maksymhryzodub-prog]

Closes CLEAN-36.

Both consoles used to make you pass through an index screen before doing the one thing you came for — talk to an agent. In admin that was a table; in app, a grid of cards. Inside an agent, admin then spent a whole column on nine settings tabs sitting permanently next to the chat.

What changes

Admin — the agents table is deleted outright. /agents is now a resolver: it picks the Ranch admin ("rancher") agent, falls back to the most recently updated, and redirects to the canonical /agents/:id. The screen becomes three parts:

• a vertical rail of agents on the left — avatar, name, live status, creation date, admin marker, plus a name search. No per-row actions: a rail entry picks an agent, it does not act on one.
• the canvas in the middle — the chat with the pod logs beside it, at the sizes they already had.
• a narrow settings navigator on the right, open by default, holding the agent's identity, the eight sections with their counts, and every lifecycle action the table's row menu used to carry (edit / start / stop / restart / delete).

App — the card grid is replaced by the same rail. No settings panel; management stays in admin. The last opened agent is remembered per browser and validated against the visible list, so a deleted or newly-hidden agent is a non-event rather than a dead landing.

The decision worth reviewing

Clicking a section renders it on the canvas, in place of the conversation — not inside the panel. The panel navigates; it does not contain.

That was the second design. The first put the sections in an accordion inside the panel, which would have meant redesigning Files (tree + editor), Paddock and Environment to fit ~400px. Rendering on the canvas gives them roughly the width they already have, so none of the eight section components changed — no markup, no styles. Worth verifying that claim against the diff; it is the main reason this PR is as small as it is.

Two invariants hold it together:

• The chat is hidden with v-show, never v-if. Unmounting would drop the websocket, the transcript, the scroll position and the restart overlay state, so returning from a section would cost a reconnect.
• The per-agent remount :key sits on the workspace's middle column, not on the page. On the page it would remount the rail on every switch, refetching the agent list and flashing the column.

Layout

Chat and logs both carried a hard 400px minimum — an 812px floor for the pair. Once the rail took its 272px, a narrower container simply overflowed and the layout's overflow-x-clip ate the chat card's right border. The floor is now gated on there being room for it (min-[1400px]); below that both halves shrink together and stay fully visible. The settings panel takes real space rather than floating, because floating covered the logs.

The workspace measures its available height instead of subtracting a hard-coded chrome value — the earlier constant broke silently when the layout's padding changed from p-6 to p-3.

Not in scope

No API change, no new DTO, no new UI dependency. The admin primary sidebar is untouched — the visual reference does not draw it, which is an artefact of the mockup rather than an instruction.

Verification

Gate
bun run typecheck	✅ 2/2
bun run i18n:check	✅ 175 keys, no undefined usages
admin / app production build	✅
Manual walkthrough	⛔ not run

The typecheck gate was itself verified with deliberate probe errors in a .ts file and in a .vue template — both were caught. The builds resolve every auto-imported component, so the wiring is checked.

What is not checked is anything only a browser shows: layout at each breakpoint, the chat surviving a section round trip without a reconnect, the rail not refetching on switch, and ?tab= deep links. specs/006-agent-workspace-tabs/quickstart.md has the 18-step walkthrough mapped to requirement ids — please run it before merging.

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