feat(pipelines): add build trigger watch mode with SSE reconnect

[fhacloid]

Summary

• add --watch, --timeout, and --cancel-on-timeout flags to cy pipeline build trigger
• implement build watch workflow that polls build status until completion and maps terminal states to script-friendly exit codes
• stream build logs from getBuildEvents as server-sent events with reconnect support and Last-Event-ID tracking
• add middleware support for opening build event streams (OpenBuildEventsStream) while keeping the existing GetBuildEvents helper
• add typed exit-code error handling in main so command-specific non-1 exit codes are preserved

Exit code mapping

• 0: build succeeded
• 1: unexpected error
• 2: build aborted
• 3: build failed (including errored)
• 4: timeout

Testing

• GOTOOLCHAIN=go1.25.1 go test ./cmd/cycloid/pipelines -count=1
• GOTOOLCHAIN=go1.25.1 go build ./...
• make lint could not run in this environment because golangci-lint is not installed (and make also attempts to auto-generate .env requiring CY_SAAS_API_KEY).

Linear Issue: CLI-3