mosaic coord: board subcommand (P3 gap closure)

Measured: coord already dispatches to framework/tools/orchestrator for
init/status/session/mission/progress/continue/next/run/start/smoke/
test/resume/recover, and prdy to framework/tools/prdy — the Q10
'collision' was never one; the npm commands already wrap the brain tool
lineage. The single gap vs tools/orchestrator was board-roll.sh: adds
coord board (+ roll alias) and the help line. P3 collapses to this
patch; build green; mission-prd specs 3/3.

packages/mosaic/src/commands/launch.ts

@@ -1162,6 +1162,8 @@ const COORD_SUBCMDS: Record<string, string> = {
   test: 'smoke-test.sh',
   resume: 'session-resume.sh',
   recover: 'session-resume.sh',
+  board: 'board-roll.sh',
+  roll: 'board-roll.sh',
 };
 
 function runCoord(args: string[]): never {
@@ -1195,6 +1197,7 @@ Commands:
   run [--project <path>]      Launch runtime with mission context
   smoke                       Run orchestration smoke checks
   resume [--project <path>]   Crash recovery
+  board                      Roll the orchestration board (board-roll.sh)
 
 Runtime: --claude (default) | --codex | --pi | --yolo`);
     process.exit(subcmd === 'help' ? 0 : 1);