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>

docs/src/internals/delivery-service.md

@@ -6,8 +6,8 @@ recipient identity key and channel identifier. The DS exposes three operations
 through the `NodeService` RPC interface: `enqueue`, `fetch`, and `fetchWait`.
 
 **Sources:**
-- `crates/quicnprotochat-server/src/main.rs` (RPC handlers)
-- `crates/quicnprotochat-server/src/storage.rs` (queue storage)
+- `crates/quicproquo-server/src/main.rs` (RPC handlers)
+- `crates/quicproquo-server/src/storage.rs` (queue storage)
 - `schemas/node.capnp` (wire schema)
 
 ---