feat(installer): build worker source over SSH

Makefile

@@ -39,12 +39,15 @@ test:
 		./checks/llmhttp
 
 # test-ssh runs the Docker/OpenSSH source-install harness tests against
-# real Alpine, Ubuntu, and Arch fixtures. Requires a working Docker
-# daemon; the fixtures pull/start containers, so this is opt-in and is
-# never part of the default `make test` run.
+# real Alpine, Ubuntu, and Arch fixtures, including the full work
+# package-3 source install (Go toolchain download, clone, and build) on
+# each. Requires a working Docker daemon; the fixtures pull/start
+# containers and build inside them, so this is opt-in and is never part
+# of the default `make test` run. The 60m timeout covers three real
+# toolchain downloads and worker builds plus the harness lifecycle tests.
 test-ssh:
 	RSMON_ENV=test CWD=$(CURDIR) RSMON_TEST_DOCKER=1 go test \
-		-v -timeout 30m -count=1 ./internal/installer/harness
+		-v -timeout 60m -count=1 ./internal/installer/harness
 
 check:
 	go mod tidy