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/labstack/echo/v4/.gitignore

@@ -0,0 +1,8 @@
+.DS_Store
+coverage.txt
+_test
+vendor
+.idea
+*.iml
+*.out
+.vscode