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/wire-format/node-service-schema.md

@@ -3,14 +3,14 @@
 **Schema file:** `schemas/node.capnp`
 **File ID:** `@0xd5ca5648a9cc1c28`
 
-The `NodeService` interface is the unified Cap'n Proto RPC surface that every quicnprotochat client talks to. It combines the Authentication Service and Delivery Service into a single interface, adds long-polling support (`fetchWait`), a health probe (`health`), and hybrid KEM key management. Every method that mutates state or accesses per-user data accepts an `Auth` struct for versioned authentication.
+The `NodeService` interface is the unified Cap'n Proto RPC surface that every quicproquo client talks to. It combines the Authentication Service and Delivery Service into a single interface, adds long-polling support (`fetchWait`), a health probe (`health`), and hybrid KEM key management. Every method that mutates state or accesses per-user data accepts an `Auth` struct for versioned authentication.
 
 ---
 
 ## Full schema listing
 
 ```capnp
-# node.capnp -- Unified quicnprotochat node RPC interface.
+# node.capnp -- Unified quicproquo node RPC interface.
 #
 # Combines Authentication and Delivery operations into a single service.
 #