chore: rename quicproquo → quicprochat in Rust workspace

Rename all crate directories, package names, binary names, proto
package/module paths, ALPN strings, env var prefixes, config filenames,
mDNS service names, and plugin ABI symbols from quicproquo/qpq to
quicprochat/qpc.

Cargo.toml

@@ -1,23 +1,23 @@
 [workspace]
 resolver = "2"
 members = [
-    "crates/quicproquo-core",
-    "crates/quicproquo-proto",
-    "crates/quicproquo-plugin-api",
-    "crates/quicproquo-kt",
-    "crates/quicproquo-rpc",
-    "crates/quicproquo-sdk",
-    "crates/quicproquo-server",
-    "crates/quicproquo-client",
+    "crates/quicprochat-core",
+    "crates/quicprochat-proto",
+    "crates/quicprochat-plugin-api",
+    "crates/quicprochat-kt",
+    "crates/quicprochat-rpc",
+    "crates/quicprochat-sdk",
+    "crates/quicprochat-server",
+    "crates/quicprochat-client",
     # P2P crate uses iroh (~90 extra deps). Only compiled when the `mesh`
-    # feature is enabled on quicproquo-client.
-    "crates/quicproquo-p2p",
+    # feature is enabled on quicprochat-client.
+    "crates/quicprochat-p2p",
 ]
 
 [workspace.package]
 edition     = "2021"
 rust-version = "1.75"
-repository  = "https://github.com/quicproquo/quicproquo"
+repository  = "https://github.com/quicprochat/quicprochat"
 description = "End-to-end encrypted group messaging over QUIC"
 keywords    = ["encryption", "messaging", "quic", "mls", "post-quantum"]
 categories  = ["cryptography", "network-programming"]