feat(FN-3249): apply run status icon color style (+3 more)

Commits merged:
- fix(FN-3249): apply run status icon color style
- fix(FN-3249): address workflow revision dashboard accessibility feedback
- feat(FN-3249): complete Step 5 — document assigned execution ownership
- feat(FN-3249): complete Step 2 — durable assigned-agent execution ownership

Files changed:
.changeset/fn-3249-assigned-executor-ownership.md  |   5 +
 docs/agents.md                                     |  15 +++
 packages/core/src/__tests__/agent-store.test.ts    |  28 +++++
 packages/core/src/agent-store.ts                   |  34 ++++--
 .../dashboard/app/components/AgentDetailView.css   |   5 +
 .../dashboard/app/components/AgentDetailView.tsx   |   2 +-
 packages/dashboard/app/components/AgentsView.tsx   |   2 +
 .../runtimes/__tests__/in-process-runtime.test.ts  | 125 ++++++++++++++++++---
 packages/engine/src/runtimes/in-process-runtime.ts | 108 +++++++++++-------
 9 files changed, 260 insertions(+), 64 deletions(-)

Fusion-Task-Id: FN-3249

packages/dashboard/app/components/AgentDetailView.css

@@ -258,6 +258,11 @@
   padding-bottom: var(--space-md);
 }
 
+.dashboard-summary-health-reason {
+  margin-left: var(--space-xs);
+  font-size: calc(var(--space-sm) + var(--space-xs));
+}
+
 .dashboard-summary-card {
   background: var(--card);
   border: 1px solid var(--border);

packages/dashboard/app/components/AgentDetailView.tsx

@@ -1393,7 +1393,7 @@ function RunsTab({
                 </button>
               )}
               <span className={cn("run-status", run.status)}>
-                <StatusIcon size={14} className={statusInfo.color} />
+                <StatusIcon size={14} style={{ color: statusInfo.color }} />
                 {run.status}
               </span>
               {run.heartbeatProcedureSource === "custom" && (

packages/dashboard/app/components/AgentsView.tsx

@@ -787,6 +787,8 @@ export function AgentsView({ addToast, projectId, onOpenTaskLogs, agentOnboardin
                 handleOpenNewAgent();
                 setIsControlsPanelOpen(false);
               }}
+              aria-label="New Agent"
+              title="New Agent"
             >
               <Plus size={16} />
               New Agent