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/getting-started/demo-walkthrough.md

@@ -75,13 +75,13 @@ You will need **three terminal windows**: one for the server, one for Alice, and
 In **Terminal 1** (Server):
 
 ```bash
-cargo run -p quicnprotochat-server
+cargo run -p quicproquo-server
 ```
 
 Wait for the log line confirming it is accepting connections:
 
 ```
-INFO quicnprotochat_server: accepting QUIC connections addr="0.0.0.0:7000"
+INFO quicproquo_server: accepting QUIC connections addr="0.0.0.0:7000"
 ```
 
 If this is the first run, you will also see a log line about generating the self-signed TLS certificate. The certificate is written to `data/server-cert.der`, which the client will use for TLS verification.
@@ -91,7 +91,7 @@ If this is the first run, you will also see a log line about generating the self
 In **Terminal 2** (Alice):
 
 ```bash
-cargo run -p quicnprotochat-client -- register-state \
+cargo run -p quicproquo-client -- register-state \
   --state alice.bin \
   --server 127.0.0.1:7000
 ```
@@ -116,7 +116,7 @@ KeyPackage uploaded successfully.
 In **Terminal 3** (Bob):
 
 ```bash
-cargo run -p quicnprotochat-client -- register-state \
+cargo run -p quicproquo-client -- register-state \
   --state bob.bin \
   --server 127.0.0.1:7000
 ```
@@ -137,7 +137,7 @@ In **Terminal 2** (Alice):
 First, create the group:
 
 ```bash
-cargo run -p quicnprotochat-client -- create-group \
+cargo run -p quicproquo-client -- create-group \
   --state alice.bin \
   --group-id "demo-chat"
 ```
@@ -151,7 +151,7 @@ Alice is now the sole member of the group at epoch 0.
 Next, invite Bob using his identity key from Step 3:
 
 ```bash
-cargo run -p quicnprotochat-client -- invite \
+cargo run -p quicproquo-client -- invite \
   --state alice.bin \
   --peer-key <BOB_KEY> \
   --server 127.0.0.1:7000
@@ -173,7 +173,7 @@ Alice's group state has now advanced to epoch 1.
 In **Terminal 3** (Bob):
 
 ```bash
-cargo run -p quicnprotochat-client -- join \
+cargo run -p quicproquo-client -- join \
   --state bob.bin \
   --server 127.0.0.1:7000
 ```
@@ -195,7 +195,7 @@ Bob is now a member of the group at epoch 1, sharing the same group secret as Al
 In **Terminal 2** (Alice):
 
 ```bash
-cargo run -p quicnprotochat-client -- send \
+cargo run -p quicproquo-client -- send \
   --state alice.bin \
   --peer-key <BOB_KEY> \
   --msg "Hello Bob, this is encrypted with MLS!" \
@@ -215,7 +215,7 @@ message sent
 In **Terminal 3** (Bob):
 
 ```bash
-cargo run -p quicnprotochat-client -- recv \
+cargo run -p quicproquo-client -- recv \
   --state bob.bin \
   --server 127.0.0.1:7000
 ```
@@ -233,7 +233,7 @@ This command:
 In **Terminal 3** (Bob):
 
 ```bash
-cargo run -p quicnprotochat-client -- send \
+cargo run -p quicproquo-client -- send \
   --state bob.bin \
   --peer-key <ALICE_KEY> \
   --msg "Hi Alice, received loud and clear!" \
@@ -249,7 +249,7 @@ message sent
 In **Terminal 2** (Alice):
 
 ```bash
-cargo run -p quicnprotochat-client -- recv \
+cargo run -p quicproquo-client -- recv \
   --state alice.bin \
   --server 127.0.0.1:7000
 ```
@@ -266,7 +266,7 @@ If you want to see the entire flow in a single command without managing three te
 
 ```bash
 # Ensure the server is running, then:
-cargo run -p quicnprotochat-client -- demo-group --server 127.0.0.1:7000
+cargo run -p quicproquo-client -- demo-group --server 127.0.0.1:7000
 ```
 
 ```