Stalled and dead Active Agents rows were previously stuck with only the live Stop action, which expects a running pid or terminal. This change adds a separate Dismiss action that deletes the matching active-session record, keeps the existing Stop flow for live sessions, mirrors the behavior into the shipped template, and bumps the extension manifest version so installs can pick up the new surface.

Constraint: Stop must remain process-oriented for live sessions; stale-row cleanup must not pretend to kill a process
Rejected: Reuse Stop for stale rows | mixes process control with sidebar-only cleanup and still wants a pid-oriented flow
Confidence: high
Scope-risk: narrow
Reversibility: clean
Directive: Keep session-only cleanup on the dismiss path and preserve gx stop semantics for live terminals or pids
Tested: node --test test/vscode-active-agents-session-state.test.js
Not-tested: Manual VS Code sidebar interaction in a live editor window