Slice 1: build green, MVP core flow

- New agentlib module (gitutil + deployer with NewGo / NewPHP) replaces
  agent-micro/internal so both agents can share it (Go's internal/ rule
  was blocking agent-gateway from importing agent-micro's packages).
- Migrate agents from legacy github.com/docker/docker/client to the
  current github.com/moby/moby/client v0.5.0 / moby/moby/api v1.55.0.
- Fix compile errors in the original committed code: missing
  gorilla/websocket import in control-plane/internal/ws/handlers.go,
  unaliased dockerclient reference, wrong SQLite driver name
  (sqlite3 -> sqlite), Dialer.Dial 3-return-value mismatch.
- scripts/build.sh: Go 1.23 -> 1.24, apk add git, safe.directory for
  bind-mounted host tree, chmod inside container (host can't chmod
  files owned by container root).
- README and REQUIREMENTS updated to reflect the actual architecture
  (Go + SQLite, no Spring Boot, moby SDK, per-deploy no image build)
  with a per-feature status checklist at the end of REQUIREMENTS.

agentlib/go.mod

@@ -0,0 +1,13 @@
+module github.com/sdp/agentlib
+
+go 1.24
+
+require (
+	github.com/docker/go-connections v0.7.0
+	github.com/gorilla/websocket v1.5.1
+	github.com/moby/moby/api v1.55.0
+	github.com/moby/moby/client v0.5.0
+	github.com/sdp/protocol v0.0.0-00010101000000-000000000000
+)
+
+replace github.com/sdp/protocol => ../protocol