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>

crates/quicproquo-client/Cargo.toml

@@ -0,0 +1,67 @@
+[package]
+name        = "quicproquo-client"
+version     = "0.1.0"
+edition     = "2021"
+description = "CLI client for quicproquo."
+license     = "MIT"
+
+[[bin]]
+name = "qpq"
+path = "src/main.rs"
+
+[dependencies]
+quicproquo-core  = { path = "../quicproquo-core" }
+quicproquo-proto = { path = "../quicproquo-proto" }
+openmls_rust_crypto = { workspace = true }
+
+# Serialisation + RPC
+capnp         = { workspace = true }
+capnp-rpc     = { workspace = true }
+
+# Async
+tokio         = { workspace = true }
+tokio-util    = { workspace = true }
+futures       = { workspace = true }
+serde         = { workspace = true }
+serde_json    = { workspace = true }
+bincode       = { workspace = true }
+
+# Crypto — OPAQUE PAKE
+opaque-ke     = { workspace = true }
+rand          = { workspace = true }
+
+# Error handling
+anyhow        = { workspace = true }
+thiserror     = { workspace = true }
+
+# Crypto — for fingerprint verification in fetch-key subcommand
+sha2          = { workspace = true }
+argon2        = { workspace = true }
+chacha20poly1305 = { workspace = true }
+zeroize       = { workspace = true }
+quinn         = { workspace = true }
+quinn-proto   = { workspace = true }
+rustls        = { workspace = true }
+
+# Logging
+tracing       = { workspace = true }
+tracing-subscriber = { workspace = true }
+
+# CLI
+clap          = { workspace = true }
+
+# Local message/conversation storage
+rusqlite      = { workspace = true }
+
+# Hex encoding/decoding
+hex           = { workspace = true }
+
+# Secure password prompting (no echo)
+rpassword     = "5"
+
+[dev-dependencies]
+dashmap       = { workspace = true }
+assert_cmd    = "2"
+tempfile      = "3"
+portpicker    = "0.1"
+rand          = "0.8"