Switch remote deploy to vendored source builds

Move remote deployment to a vendored source bundle built on the target host via Docker so redeploys no longer require local cross-compilation or host Go installation.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

vendor/github.com/valyala/bytebufferpool/.travis.yml

@@ -0,0 +1,15 @@
+language: go
+
+go:
+  - 1.6
+
+script:
+  # build test for supported platforms
+  - GOOS=linux go build
+  - GOOS=darwin go build
+  - GOOS=freebsd go build
+  - GOOS=windows go build
+  - GOARCH=386 go build
+
+  # run tests on a standard platform
+  - go test -v ./...