Add DevListenServer TCP listener with hello/ping handshake

[mblackman]

Summary

Stage 6 PR-A of ai/EditorBuildAndDeployPlan.md — foundation for the dev-iterate loop. TCP listener the editor (and other tooling) will dial into for asset / script push and Lua eval. This PR ships the socket + thread infrastructure and the hello + ping ops; PR-B will land eval_lua / reload_scene / push_script / push_asset.

• New src/Dev/DevListenServer.{h,cpp} — Registry singleton, listener thread bound to 127.0.0.1:<port> (or 0.0.0.0 with --dev-listen-all). Compile-stripped from ship builds via #ifndef OCTARINE_SHIPPED on header / .cpp / CMake / Game / Main.
• Wire v1: little-endian u32 length | u32 op | body[length-4].
  • Hello returns a versioned banner string so clients can gate on protocol version.
  • Ping echoes the client's nonce body back.
  • Reserved op ids for PR-B (10 EvalLua, 11 ReloadScene, 12 PushScript, 13 PushAsset) noted in code so we don't reuse them.
• BSD sockets on POSIX, Winsock on Windows (ws2_32 linked, WSAStartup refcounted so tests + engine share one init).
• CLI: --dev-listen <port> opts in; --dev-listen-all flips the bind to 0.0.0.0 with a loud Logger::Warn. Both flags log a "stripped by shipped build" warning when seen in a shipped binary and parse no-op so they cannot eat a CLI slot.
• Pump() runs on the main thread per frame; PR-A has nothing to drain through it. PR-B will SPSC the not-thread-safe ops (Lua eval, scene reload, asset writes) through it.

Out of scope (PR-B + later):

• Real ops (eval_lua / reload_scene / push_script / push_asset)
• JSON dep (PR-A wire stays binary; PR-B can pull nlohmann-json if metadata needs it)
• Editor-side client (Devices panel from Stage 8)

Test plan

• cmake --preset editor-debug -DOCTARINE_ENABLE_TESTS=ON && cmake --build build/editor-debug --target OctarineDevListenServerTest — clean compile on Windows. ws2_32 links.
• ctest -R DevListenServerTest — green locally (0.01s). Asserts: Start on ephemeral port, Hello banner roundtrip, Ping echoes nonce, Stop joins thread cleanly, Stop+Start cycle clean.
• Editor-debug + ship-release symbol surface: shipped build does not link ws2_32 (CMake guard) and does not compile the .cpp (SRC_FILES guard).
• Manual: launch editor with --dev-listen 9001, dial in with python -c "import socket,struct; s=socket.create_connection(('127.0.0.1',9001)); s.send(struct.pack('<II',4,1)); print(s.recv(256))", observe banner.
• CI: cross-platform legs prove POSIX-socket path compiles on Linux + macOS and the test runs on each.