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>

Cargo.toml

@@ -1,16 +1,17 @@
 [workspace]
 resolver = "2"
 members = [
-    "crates/quicnprotochat-core",
-    "crates/quicnprotochat-proto",
-    "crates/quicnprotochat-server",
-    "crates/quicnprotochat-client",
-    "crates/quicnprotochat-gui",
+    "crates/quicproquo-core",
+    "crates/quicproquo-proto",
+    "crates/quicproquo-server",
+    "crates/quicproquo-client",
+    "crates/quicproquo-gui",
+    "crates/quicproquo-mobile",
 ]
 # P2P-Crate (iroh-Transport) ist vom Default-Build ausgeschlossen,
 # um ~90 exklusive iroh-Dependencies nicht mitzukompilieren.
 # Quellcode bleibt im Repo für spätere Integration.
-exclude = ["crates/quicnprotochat-p2p"]
+exclude = ["crates/quicproquo-p2p"]
 
 # Shared dependency versions — bump here to affect the whole workspace.
 [workspace.dependencies]
@@ -55,6 +56,9 @@ rcgen              = { version = "0.13" }
 # ── Database ─────────────────────────────────────────────────────────────
 rusqlite           = { version = "0.31", features = ["bundled-sqlcipher"] }
 
+# ── Encoding ─────────────────────────────────────────────────────────────────
+hex                = { version = "0.4" }
+
 # ── Server utilities ──────────────────────────────────────────────────────────
 dashmap            = { version = "5" }
 tracing            = { version = "0.1" }