fix: Windows compatibility for qodercli

[shadowericq]

Summary

This PR fixes the opencode-qoder-auth plugin to work on Windows with qodercli installed via npm.

Root Cause Chain (4 sequential failures)

1. resolveQoderCLI() only searched for bare qodercli — on Windows, the binary is qodercli.exe
2. --print mode caused ENAMETOOLONG on Windows (command line limit ~32767 chars)
3. --verbose flag not supported by qodercli → exit code 1
4. Multiple SDK flags (--storage-dir, --resource-dir, etc.) not supported by qodercli → silent failures

Changes

src/qoder-language-model.ts

• Fix resolveQoderCLI(): On Windows, search for qodercli.exe first, then .cmd, then bare name. Also check npm global package embedded binary path (%APPDATA%\npm\node_modules\@qoder-ai\qodercli\bin\qodercli.exe)
• Add wrapStringAsStream(): Forces streaming input mode (--input-format stream-json) instead of --print, avoiding Windows ENAMETOOLONG for long prompts
• Force streaming in doStream(): String prompts are wrapped as async iterables so SDK uses stdin-based input

src/vendor/qoder-agent-sdk.mjs

• Remove --verbose from buildCommand() — not supported by qodercli
• Remove unsupported CLI flags: --storage-dir, --resource-dir, --max-turns, --max-budget-usd, --fallback-model, --betas, --resume-session-at, --include-partial-messages, --max-thinking-tokens, --json-schema
• Add --mcp-config temp file fallback: When MCP config JSON exceeds 8000 chars, write to temp file instead of passing inline (avoids ENAMETOOLONG on Windows)

Testing

• ✅ CLI resolution finds qodercli.exe on Windows
• ✅ Streaming mode (--input-format stream-json) works from Node.js spawn
• ✅ End-to-end: CLI returns result success with exit code 0
• ✅ Plugin loads without ProviderInitError in opencode

Known Limitations

• qodercli 0.2.7 does not emit stream_event messages — only complete assistant messages. This means no token-by-token streaming; the full response appears at once. This is a CLI limitation, not a plugin issue.