Show task, active project and workspace per control board row (#1503)

Gate A fix asked by the professor session on Jason's behalf. Each row
now carries three derived fields, shown as "unknown" when the log and
tmux do not hold them:

- task: the session's first user message (pi logs have no task envelope)
- workspace: the live pane path of the pane running pi, else session cwd
- activeProject: basename of the nearest git checkout above the workspace

tmuxInspect replaces the bare liveness call in the CLI and returns
{ alive, workspace }; tmuxIsAlive stays as a wrapper. The grouping column
and seen.json keys are unchanged. Fixture test per field, tmux parse
tests, page test; missing launcher signals are recorded in the plan page.

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

packages/control-board/src/cli.mjs

@@ -5,7 +5,7 @@
 // Exit 0 on success, 2 on a config refusal or bad usage.
 import { join } from "node:path";
 import { homedir } from "node:os";
-import { loadConfig, defaultConfigPath, discoverRepoAgents, discoverFleetAgents, scan, tmuxIsAlive, ConfigError } from "./scan.mjs";
+import { loadConfig, defaultConfigPath, discoverRepoAgents, discoverFleetAgents, scan, tmuxInspect, ConfigError } from "./scan.mjs";
 import { startServer } from "./serve.mjs";
 
 const USAGE = "usage: mosaic-board scan|serve [--config PATH] [--repo PATH] [--fleet PATH|none] [--liveness tmux|assume-alive] [--print] [--port N] [--host 127.0.0.1]";
@@ -38,7 +38,7 @@ async function main() {
   const opts = parseArgs(process.argv.slice(2));
   const { dataRoot } = loadConfig(opts.config);
   const specs = [...discoverRepoAgents(opts.repo), ...(opts.fleet === "none" ? [] : discoverFleetAgents(opts.fleet))];
-  const isAlive = opts.liveness === "tmux" ? tmuxIsAlive : () => true;
+  const isAlive = opts.liveness === "tmux" ? tmuxInspect : () => true;
   const boardDir = join(dataRoot, "board");
   if (opts.command === "serve") {
     const server = await startServer({ host: opts.host, port: opts.port, specs, boardDir, isAlive });