feat(providers): add Qwen Code CLI provider

[ntheanh201]

Summary

Add qwen_cli provider type that shells out to the local qwen binary,
mirroring the Claude CLI integration pattern.

• Provider implementation with streaming support and session resumption
• Session file detection at ~/.qwen/projects//chats/.jsonl
• OAuth auth status endpoint at /v1/providers/qwen-cli/auth-status
• UI support: provider form, auth status section, i18n (en/vi/zh)
• Container support: qwen binary pre-installed, credential sync in entrypoint

Type

• Feature
• Bug fix
• Hotfix (targeting main)
• Refactor
• Docs
• CI/CD

Target Branch

dev

Checklist

• go build ./... passes
• go build -tags sqliteonly ./... passes (if Go changes)
• go vet ./... passes
• Tests pass: go test -race ./...
• Web UI builds: cd ui/web && pnpm build (if UI changes)
• No hardcoded secrets or credentials
• SQL queries use parameterized $1, $2 (no string concat)
• New user-facing strings added to all 3 locales (en/vi/zh)
• Migration version bumped in internal/upgrade/version.go (if new migration)

Test Plan

1. Add qwen_cli provider via UI
2. Restart goclaw to register provider
3. Create/update agent to use qwen provider
4. Send chat message — verify first message succeeds
5. Send second message — verify session resumes (no "Session Id already in use" error)
6. Check auth status at GET /v1/providers/qwen-cli/auth-status