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/design-rationale/adr-004-mls-unaware-ds.md

@@ -40,7 +40,7 @@ The RFC explicitly envisions that the DS operates on opaque blobs, not on decryp
 
 ## Decision
 
-The quicnprotochat Delivery Service is **MLS-unaware**. It routes opaque byte strings by `(recipientKey, channelId)` without parsing, inspecting, or validating any MLS content.
+The quicproquo Delivery Service is **MLS-unaware**. It routes opaque byte strings by `(recipientKey, channelId)` without parsing, inspecting, or validating any MLS content.
 
 ### What the DS sees
 
@@ -109,8 +109,8 @@ This means that sending a message to a group of n members requires n-1 enqueue c
 |---|---|
 | `schemas/delivery.capnp` | DeliveryService RPC interface (opaque `Data` payloads) |
 | `schemas/node.capnp` | NodeService: `enqueue`, `fetch`, `fetchWait` methods |
-| `crates/quicnprotochat-server/src/storage.rs` | Server-side queue storage (DashMap-based FIFO queues) |
-| `crates/quicnprotochat-server/src/main.rs` | NodeService RPC handler implementation |
+| `crates/quicproquo-server/src/storage.rs` | Server-side queue storage (DashMap-based FIFO queues) |
+| `crates/quicproquo-server/src/main.rs` | NodeService RPC handler implementation |
 
 ---