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/cryptography/key-lifecycle.md

@@ -1,6 +1,6 @@
 # Key Lifecycle and Zeroization
 
-quicnprotochat uses multiple key types with different lifetimes, creation
+quicproquo uses multiple key types with different lifetimes, creation
 patterns, and destruction guarantees. This page provides a comprehensive
 lifecycle diagram for every key type in the system, from generation through
 zeroization.
@@ -25,7 +25,7 @@ Hybrid KEM Keys       Per peer (future)   Public portion       X25519+ML-KEM-768
 
 ## Ed25519 Identity Key
 
-**Source:** `crates/quicnprotochat-core/src/identity.rs`
+**Source:** `crates/quicproquo-core/src/identity.rs`
 
 The Ed25519 identity key is the most long-lived secret in the system. It
 represents the client's cryptographic identity across all sessions and groups.
@@ -92,8 +92,8 @@ zeroization.
 
 ## HPKE Init Keys
 
-**Source:** `crates/quicnprotochat-core/src/keystore.rs` and
-`crates/quicnprotochat-core/src/group.rs`
+**Source:** `crates/quicproquo-core/src/keystore.rs` and
+`crates/quicproquo-core/src/group.rs`
 
 HPKE init keys are generated by the openmls backend as part of MLS KeyPackage
 creation. They are single-use: each init key is consumed exactly once when
@@ -167,7 +167,7 @@ processing a Welcome message.
 **Managed by:** `openmls` (internal to the `MlsGroup` state machine)
 
 MLS epoch keys are derived internally by the openmls ratchet tree. They are not
-directly accessible in quicnprotochat code but are critical to understanding the
+directly accessible in quicproquo code but are critical to understanding the
 system's security properties.
 
 ### Lifecycle
@@ -216,12 +216,12 @@ system's security properties.
 - **Deletion:** Old epoch keys are deleted after the Commit is processed. This
   deletion is what provides [forward secrecy](forward-secrecy.md) at the MLS
   layer.
-- **No direct access:** quicnprotochat code interacts with epoch keys only
+- **No direct access:** quicproquo code interacts with epoch keys only
   indirectly through `send_message()` and `receive_message()`.
 
 ## Hybrid KEM Keys (Future -- M5+)
 
-**Source:** `crates/quicnprotochat-core/src/hybrid_kem.rs`
+**Source:** `crates/quicproquo-core/src/hybrid_kem.rs`
 
 The hybrid KEM keypair combines X25519 (classical) with ML-KEM-768
 (post-quantum) for content encryption that resists both classical and quantum