control board: show the model each seat is running (#1503)

Jason asked for the running model (sonnet, opus, gpt-6-astra) on the
board. readSession keeps model and provider from the log's latest
model_change entry or assistant turn, whichever is later, so a /model
switch shows on the next scan; scanAgent exposes both; the page shows the
model under the agent name with the provider in the hover and a Model
detail row. Blank when the log names none.

Live check on a scratch board against the real data root: all 42 rows
carried a model. Board 91/91. Sonnet review caught a double-escaped hover
title; fixed.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

docs/SESSIONS.md

@@ -222,3 +222,4 @@ are never rewritten or removed; corrections are new entries.
 - 2026-09-12 — jarvis (Claude Code, coordinator) — Control board step 3, Gate A fix (#1503), asked by the professor session on Jason's behalf: per-row Task (first user message), Active project (nearest git checkout above the workspace) and Workspace (live tmux pane path, else session cwd), "unknown" when not derivable; missing launcher signals logged on the plan page. Fixture test per field (79/79); live check on a scratch server; sonnet review APPROVED (no findings).
 - 2026-09-12 — darkwing (Claude Code, coordinator; formerly jarvis) — Seat registration (#1504), Jason's go on the professor session's brief: new `packages/seat` and `scripts/mosaic` (`launch <seat>` registers then execs the launch script unchanged; `seat task` edits the task); board reads `<dataRoot>/seats/<layout>/<seat>/registration.json` and lets registered task/project/workspace override derived values with a source tag; the four repo launch scripts register themselves; fleet one-liner written for orch-01. Tests: seat 15, board 79 → 89, launch scripts 5, registry 69, config 24. Sonnet review found a seat-name collision across layouts; fixed by keying on layout, second pass APPROVED. Live check on a scratch server against a temp data root. Also found Jason's launch refused on the Pi pin (node_modules 0.84.4 vs pin 0.85.1 since 557aba0f); `npm ci` fixed it, the refusal now names both versions; the pin stays unless Jason decides otherwise.
 - 2026-09-12 — darkwing (Claude Code, coordinator) — #1504 follow-up on two defects the professor session reported and this session verified: the darkwing launch test leaked fixture registrations into the real data root (flock spawn without the fixture config; fixed and guarded so a leak fails), and a refused launch left a dead-pid record the board honoured (scanner now probes the pid; stale records are shown but do not override). Fleet launchers marked not planned per Jason. Board 90/90, seat 15/15, launch scripts 5/5. Committed and pushed to refactor.
+- 2026-09-12 — darkwing (Claude Code, coordinator) — Control board: model per row (#1503) on Jason's ask: readSession tracks model/provider from the latest model_change entry or assistant turn; page shows the model under the agent name and a Model detail row. Live check on a scratch board: all 42 real rows named a model. Board 91/91. Committed and pushed to refactor.