fix: Alpine parliament Docker build (musl clean rebuild)

Ignore/clean host objects, add linux-headers, and include sys/time.h
so discover builds under musl. Docker chair↔member handshake now passes.

Co-authored-by: Cursor <cursoragent@cursor.com>

.dockerignore

@@ -6,12 +6,17 @@ dist/
 third_party/
 backups/
 reports/
-*.o
-*.a
-cst-agent
+**/*.o
+**/*.a
+**/cst-agent
 tests/test_*
 !tests/test_*.c
 app/
 .cursor/
 *.apk
 *.tar.gz
+.gen/
+vendor/sashidown/*.o
+vendor/sashidown/*.a
+vendor/cjson/*.o
+vendor/monocypher/*.o