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/design-rationale/adr-005-single-use-keypackages.md

@@ -100,8 +100,8 @@ This is a defense-in-depth measure. In practice, MLS's own signature verificatio
 |---|---|
 | `schemas/auth.capnp` | `AuthenticationService` interface: `uploadKeyPackage`, `fetchKeyPackage` |
 | `schemas/node.capnp` | `NodeService` interface: same methods with `Auth` parameter |
-| `crates/quicnprotochat-server/src/storage.rs` | Server-side KeyPackage storage (DashMap-backed queue) |
-| `crates/quicnprotochat-server/src/main.rs` | RPC handler: `fetchKeyPackage` implementation with atomic removal |
+| `crates/quicproquo-server/src/storage.rs` | Server-side KeyPackage storage (DashMap-backed queue) |
+| `crates/quicproquo-server/src/main.rs` | RPC handler: `fetchKeyPackage` implementation with atomic removal |
 
 ---