feat(fleet): add durable tmux fleet poc

scratchpads/2026-06-19-tmux-fleet-durable-install-plan.md

@@ -714,14 +714,14 @@ The implementation is complete when:
 
 ## Risks and mitigations
 
-| Risk                                                | Mitigation                                                                        |
-| --------------------------------------------------- | --------------------------------------------------------------------------------- |
-| Killing existing tmux sessions                      | Use named `mosaic-factory` socket; no default `tmux kill-server`.                 |
-| systemd unit quoting/env expansion bugs             | Move logic into shell wrappers; verify with `systemd-analyze --user verify`.      |
-| Runtime reset command mismatch                      | Make reset command runtime-configurable; fallback to service restart + kickstart. |
-| Tool install drift                                  | Ensure npm package includes framework tmux/fleet tools; add packaging test.       |
-| Mosaic-specific assumptions leak into generic guide | Keep USC roster as example profile; AI Guide documents pattern/options.           |
-| Matrix migration blocked by tmux coupling           | Add `mosaic agent` abstraction now; keep tmux details below transport layer.      |
+| Risk | Mitigation |
+|---|---|
+| Killing existing tmux sessions | Use named `mosaic-factory` socket; no default `tmux kill-server`. |
+| systemd unit quoting/env expansion bugs | Move logic into shell wrappers; verify with `systemd-analyze --user verify`. |
+| Runtime reset command mismatch | Make reset command runtime-configurable; fallback to service restart + kickstart. |
+| Tool install drift | Ensure npm package includes framework tmux/fleet tools; add packaging test. |
+| Mosaic-specific assumptions leak into generic guide | Keep USC roster as example profile; AI Guide documents pattern/options. |
+| Matrix migration blocked by tmux coupling | Add `mosaic agent` abstraction now; keep tmux details below transport layer. |
 
 ## Suggested first PR split