chore: rename project quicnprotochat -> quicproquo (binaries: qpq)

Rename the entire workspace:
- Crate packages: quicnprotochat-{core,proto,server,client,gui,p2p,mobile} -> quicproquo-*
- Binary names: quicnprotochat -> qpq, quicnprotochat-server -> qpq-server,
  quicnprotochat-gui -> qpq-gui
- Default files: *-state.bin -> qpq-state.bin, *-server.toml -> qpq-server.toml,
  *.db -> qpq.db
- Environment variable prefix: QUICNPROTOCHAT_* -> QPQ_*
- App identifier: chat.quicnproto.gui -> chat.quicproquo.gui
- Proto package: quicnprotochat.bench -> quicproquo.bench
- All documentation, Docker, CI, and script references updated

HKDF domain-separation strings and P2P ALPN remain unchanged for
backward compatibility with existing encrypted state and wire protocol.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

crates/quicproquo-gui/tauri.conf.json

@@ -0,0 +1,24 @@
+{
+  "$schema": "https://schema.tauri.app/config/2",
+  "productName": "qpq-gui",
+  "identifier": "chat.quicproquo.gui",
+  "build": {
+    "frontendDist": "./ui",
+    "beforeBuildCommand": "",
+    "beforeDevCommand": ""
+  },
+  "app": {
+    "windows": [
+      {
+        "title": "quicproquo",
+        "width": 640,
+        "height": 480
+      }
+    ],
+    "security": {
+      "csp": null
+    }
+  },
+  "bundle": {},
+  "plugins": {}
+}