feat(ecc2): implement agent status panel with Table widget (#773)

- Table widget with columns: ID, Agent, State, Branch, Tokens, Duration
- Color-coded states: green=Running, yellow=Idle, red=Failed, gray=Stopped, blue=Completed
- Summary bar with running/completed/failed counts
- Row selection highlighting

ecc2/src/session/manager.rs

@@ -281,6 +281,8 @@ mod tests {
             session_timeout_secs: 60,
             heartbeat_interval_secs: 5,
             default_agent: "claude".to_string(),
+            cost_budget_usd: 10.0,
+            token_budget: 500_000,
             theme: Theme::Dark,
         }
     }