v0.1.5

Ports the AgentRouter v2.5.0 recovery fixes to OpenCode.

• Monthly spend is now reported in USD; it was 500,000× too high.
• Mid-stream response.failed frames with no error payload get an upstream_cluster_crash error.
• Requests identify as opencode/agentrouter (...).
• Interrupted streams retry after 30s, up to 3 attempts.
• Duplicate header entries are collapsed.
• /agentrouter_check shows Beijing quota refresh countdowns.