Make OpenCode HTTP request timeout configurable

[myagizmaktav]

Summary

Pilot currently hardcodes the OpenCode HTTP client timeout to 10 minutes in the backend. When OpenCode takes longer to return message response headers or stream setup, execution fails with:

context deadline exceeded (Client.Timeout exceeded while awaiting headers)

Why this matters

OpenCode task execution time can vary significantly by repository size, provider latency, and task complexity. A fixed 10-minute HTTP timeout is too rigid for long-running sessions.

Proposed behavior

Add a config option under:

executor:
  opencode:
    request_timeout: 20m

Behavior:

• default remains 10m for backward compatibility
• configurable via YAML
• invalid or empty values fall back to 10m
• used by the OpenCode backend HTTP client for session/message requests

Reproduction context

With current behavior, recent local runs failed after the schema issue was fixed, but then hit:

Post \"http://127.0.0.1:44096/session/.../message\": context deadline exceeded (Client.Timeout exceeded while awaiting headers)

This indicates the payload is accepted, but the request lifetime is too short for some runs.

Scope

This is specifically about OpenCode backend HTTP request timeout, not the broader task execution timeout routing already present under executor.timeout.

[myagizmaktav]

Implemented in PR #2411.

What it adds:

• executor.opencode.request_timeout
• default remains 10m for backward compatibility
• invalid or empty values fall back to 10m

Example:

executor:
  opencode:
    request_timeout: 20m

Verified with focused executor tests and make build.

PR: #2411