Align native Xray with xray-core; drop dead knobs; split admin app.js

Fix the two reliability problems in the in-process Xray emulator by matching
XTLS/Xray-core's transport semantics:

- XHTTP upload queue: rewrite as a faithful port of xray-core's uploadQueue
  (bounded channel + sequence reorder heap). Packet-up POSTs are now acked
  immediately on buffering instead of blocking until the tunnel reader consumes
  them. The old block-until-consumed behavior throttled the uplink to the
  reassembly rate and deadlocked against the client's concurrent-POST limit,
  which showed up as "download a burst, stall, repeat" on video/large downloads.
- Mux: dial the backend and pump uplink on a per-session goroutine fed by a
  bounded channel (mirrors xray-core's per-session buffered pipe). Previously the
  dial and backend writes ran inline in the shared read loop, so one slow target
  or backpressured session stalled every other muxed session.
- XHTTP download writer: flush every write (matches httpServerConn.Write) instead
  of batching behind a 2ms/32KB window.
- XHTTP: enforce a single download (stream-down) per session to stop two GETs
  from splitting the decoded stream and corrupting the tunnel.
- Fix a close-of-closed-channel race in the mux session teardown (sync.Once).

Remove the now-inert XHTTP tuning knobs (xhttp_queue_timeout_ms, xhttp_flush_ms,
xhttp_flush_bytes) from the backend struct and the admin panel UI.

Split admin/assets/app.js into ordered classic-script modules under
admin/assets/js/ for maintainability. The concatenation is byte-identical to the
old file and load order is preserved via defer, so behavior is unchanged.

Add regression tests for the mux head-of-line stall and the out-of-order
packet-up burst-stall; add golang.org/x/text to go.mod so tests build.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

admin/index.html

@@ -1191,6 +1191,7 @@
           <details style="margin-top:10px;" open>
             <summary style="cursor:pointer;font-size:.76rem;font-weight:700;color:var(--text);">Native Xray scale tuning</summary>
             <div class="grid2" style="margin-top:10px;gap:8px;">
+              <div class="field"><label>Go CPU threads (GOMAXPROCS)</label><input type="number" min="0" id="cfgXrayRuntimeGomaxprocs" placeholder="0 = all CPU cores"/></div>
               <div class="field"><label>Mux sessions per connection</label><input type="number" min="1" id="cfgXrayMuxMaxSessions" placeholder="128"/></div>
               <div class="field"><label>Global mux backend sessions</label><input type="number" min="1" id="cfgXrayMuxGlobalSessions" placeholder="32768"/></div>
               <div class="field"><label>Mux UDP idle ms</label><input type="number" min="1000" id="cfgXrayMuxUdpIdleMs" placeholder="15000"/></div>
@@ -1198,9 +1199,6 @@
               <div class="field"><label>Mux UDP write buffer bytes</label><input type="number" min="4096" id="cfgXrayMuxUdpWbuf" placeholder="262144"/></div>
               <div class="field"><label>XHTTP max active sessions</label><input type="number" min="1" id="cfgXrayXhttpMaxSessions" placeholder="16384"/></div>
               <div class="field"><label>XHTTP buffered posts</label><input type="number" min="1" id="cfgXrayXhttpBufferedPosts" placeholder="64"/></div>
-              <div class="field"><label>XHTTP queue timeout ms</label><input type="number" min="10" id="cfgXrayXhttpQueueTimeoutMs" placeholder="250"/></div>
-              <div class="field"><label>XHTTP flush ms</label><input type="number" min="1" id="cfgXrayXhttpFlushMs" placeholder="5"/></div>
-              <div class="field"><label>XHTTP flush bytes</label><input type="number" min="1024" id="cfgXrayXhttpFlushBytes" placeholder="131072"/></div>
               <div class="field"><label>HTTP/2 max streams</label><input type="number" min="1" id="cfgXrayH2MaxStreams" placeholder="1024"/></div>
               <div class="field"><label>HTTP/2 upload buffer / conn</label><input type="number" min="65536" id="cfgXrayH2UploadConn" placeholder="1048576"/></div>
               <div class="field"><label>HTTP/2 upload buffer / stream</label><input type="number" min="32768" id="cfgXrayH2UploadStream" placeholder="262144"/></div>
@@ -1209,7 +1207,7 @@
                 <button class="btn btn-ghost btn-sm" type="button" onclick="setXrayNativeTuningDefaults('2k')">Apply 2K defaults</button>
                 <button class="btn btn-ghost btn-sm" type="button" onclick="setXrayNativeTuningDefaults('safe')">Apply safe defaults</button>
               </div>
-              <div class="hint" style="grid-column:1/-1;margin-top:-4px;">These values are saved in the panel config and applied live on restart/reload. No systemd Environment lines are needed.</div>
+              <div class="hint" style="grid-column:1/-1;margin-top:-4px;">These values are saved in the panel config and applied live on restart/reload. Go CPU threads = 0 means all detected CPU cores. No systemd Environment lines are needed.</div>
             </div>
           </details>
         </div>
@@ -1235,6 +1233,18 @@
 </div><!-- /shell -->
 </div><!-- /app -->
 
-<script defer src="assets/app.js?v=20260704xrayadmintune2"></script>
+<!-- app.js was split into ordered modules for maintainability. They are plain
+     classic scripts sharing one global scope; `defer` preserves execution order,
+     so behavior is identical to the old single file. Keep this load order. -->
+<script defer src="assets/js/01-core.js?v=20260704ytquicfix1"></script>
+<script defer src="assets/js/02-shell.js?v=20260704ytquicfix1"></script>
+<script defer src="assets/js/03-ssh-users.js?v=20260704ytquicfix1"></script>
+<script defer src="assets/js/04-xray.js?v=20260704ytquicfix1"></script>
+<script defer src="assets/js/05-resellers.js?v=20260704ytquicfix1"></script>
+<script defer src="assets/js/06-servers.js?v=20260704ytquicfix1"></script>
+<script defer src="assets/js/07-stats-logs.js?v=20260704ytquicfix1"></script>
+<script defer src="assets/js/08-server-config.js?v=20260704ytquicfix1"></script>
+<script defer src="assets/js/09-xray-wizard.js?v=20260704ytquicfix1"></script>
+<script defer src="assets/js/10-boot.js?v=20260704ytquicfix1"></script>
 </body>
 </html>