Closes CODAGT-802
Coder Agents only escalated failed workspace dials when the agent had
connected and later disconnected. An agent that never connected and had
already exceeded its `connection_timeout` stayed on the soft retry error
indefinitely, so a chat could keep attempting tools against an unhealthy
workspace.
To fix, we'll classify the latest agent after a failed dial and return
stop/start recovery guidance when its status is `timeout`. Agents still
connecting, including templates with `connection_timeout = 0`, keep the
existing retryable behaviour.
## Before
<img width="843" height="229" alt="image"
src="https://github.com/user-attachments/assets/d659a376-c8d4-4983-b7d7-d1a699770dfb"
/>
## After
<img width="848" height="250" alt="image"
src="https://github.com/user-attachments/assets/26b88f72-f67c-4d9e-87b1-51d701b7352f"
/>
Ethan
21d08241e9