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/group-member-lifecycle.md

@@ -1,12 +1,12 @@
 # GroupMember Lifecycle
 
-The `GroupMember` struct in `quicnprotochat-core` is the core MLS state machine
+The `GroupMember` struct in `quicproquo-core` is the core MLS state machine
 that manages a single client's membership in an MLS group. It wraps an openmls
 `MlsGroup`, a persistent crypto backend, and the long-term Ed25519 identity
 keypair. Every MLS operation -- key package generation, group creation, member
 addition, joining, sending, and receiving -- flows through this struct.
 
-**Source:** `crates/quicnprotochat-core/src/group.rs`
+**Source:** `crates/quicproquo-core/src/group.rs`
 
 ---