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.

crates/quicprochat-kt/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name        = "quicprochat-kt"
+version     = "0.1.0"
+edition.workspace     = true
+description = "Key Transparency: append-only SHA-256 Merkle log for (username, identity_key) bindings."
+license     = "Apache-2.0 OR MIT"
+repository.workspace  = true
+
+[lints]
+workspace = true
+
+[dependencies]
+sha2      = { workspace = true }
+thiserror = { workspace = true }
+serde     = { workspace = true }
+bincode   = { workspace = true }