Transparent proxy mode (#823)

Adds a **transparent TCP proxy mode** to zenserver (activated via `zenserver proxy`), allowing it to sit between clients and upstream Zen servers to inspect and monitor HTTP/1.x traffic in real time. Primarily useful during development, to be able to observe multi-server/client interactions in one place.

- **Dedicated proxy port** -- Proxy mode defaults to port 8118 with its own data directory to avoid collisions with a normal zenserver instance.
- **TCP proxy core** (`src/zenserver/proxy/`) -- A new transparent TCP proxy that forwards connections to upstream targets, with support for both TCP/IP and Unix socket listeners. Multi-threaded I/O for connection handling. Supports Unix domain sockets for both upstream/downstream.
- **HTTP traffic inspection** -- Parses HTTP/1.x request/response streams inline to extract method, path, status, content length, and WebSocket upgrades without breaking the proxied data.
- **Proxy dashboard** -- A web UI showing live connection stats, per-target request counts, active connections, bytes transferred, and client IP/session ID rollups.
- **Server mode display** -- Dashboard banner now shows the running server mode (Zen Proxy, Zen Compute, etc.).

Supporting changes included in this branch:

- **Wildcard log level matching** -- Log levels can now be set per-category using wildcard patterns (e.g. `proxy.*=debug`).
- **`zen down --all`** -- New flag to shut down all running zenserver instances; also used by the new `xmake kill` task.
- Minor test stability fixes (flaky hash collisions, per-thread RNG seeds).
- Support ZEN_MALLOC environment variable for default allocator selection and switch default to rpmalloc
- Fixed sentry-native build to allow LTO on Windows

1 files changed, 18 insertions, 4 deletions

diff --git a/xmake.lua b/xmake.lua
index dfe383c1a..e9bed93aa 100644
--- a/xmake.lua
+++ b/xmake.lua
@@ -130,11 +130,8 @@ enable_unity = false
 
 if is_mode("release") then
     -- LTO does not appear to work with the current Linux UE toolchain
-    -- It's currently also temporarily disabled on Windows to investigate 
-    -- build issues due to git apply not applying the necessary patches correctly
-    -- in CI for some reason.
     -- Also, disabled LTO on Mac to reduce time spent building openssl tests
-    if not is_plat("linux", "windows", "macosx") then
+    if not is_plat("linux", "macosx") then
         set_policy("build.optimization.lto", true)
     end
     set_optimize("fastest")
@@ -352,6 +349,23 @@ task("bundle")
         bundle()
     end)
 
+task("kill")
+    set_menu {
+        usage = "xmake kill",
+        description = "Terminate any running zenserver instances",
+    }
+    on_run(function ()
+        local ok = try { function() os.execv("xmake", {"run", "zen", "down", "--all"}) end }
+        if ok then return end
+        if is_host("windows") then
+            ok = try { function() os.runv("taskkill", {"/F", "/IM", "zenserver.exe"}) end }
+            if ok then print("zenserver terminated") end
+        else
+            ok = try { function() os.runv("pkill", {"-f", "zenserver"}) end }
+            if ok then print("zenserver terminated") end
+        end
+    end)
+
 task("updatefrontend")
     set_menu {
         usage = "xmake updatefrontend",