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-proto/build.rs

@@ -0,0 +1,69 @@
+//! Build script for quicprochat-proto.
+//!
+//! Runs two code generators:
+//! 1. Cap'n Proto (v1 legacy) — from `schemas/*.capnp`
+//! 2. Protobuf/prost (v2) — from `proto/qpc/v1/*.proto`
+
+use std::{env, path::PathBuf};
+
+fn main() {
+    // Vendor protoc from protobuf-src so the build doesn't require system protoc.
+    std::env::set_var("PROTOC", protobuf_src::protoc());
+
+    let manifest_dir =
+        PathBuf::from(env::var("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR"));
+    let workspace_root = manifest_dir
+        .join("../..")
+        .canonicalize()
+        .expect("canonicalize workspace root");
+
+    // ── v1: Cap'n Proto codegen ──────────────────────────────────────────────
+    let schemas_dir = workspace_root.join("schemas");
+
+    for schema in &["auth.capnp", "delivery.capnp", "node.capnp", "federation.capnp"] {
+        println!("cargo:rerun-if-changed={}", schemas_dir.join(schema).display());
+    }
+
+    capnpc::CompilerCommand::new()
+        .src_prefix(&schemas_dir)
+        .file(schemas_dir.join("auth.capnp"))
+        .file(schemas_dir.join("delivery.capnp"))
+        .file(schemas_dir.join("node.capnp"))
+        .file(schemas_dir.join("federation.capnp"))
+        .run()
+        .expect(
+            "Cap'n Proto schema compilation failed. \
+             Is `capnp` installed? (apt-get install capnproto / brew install capnp)",
+        );
+
+    // ── v2: Protobuf/prost codegen ───────────────────────────────────────────
+    let proto_dir = workspace_root.join("proto");
+
+    let proto_files = [
+        "qpc/v1/common.proto",
+        "qpc/v1/auth.proto",
+        "qpc/v1/delivery.proto",
+        "qpc/v1/keys.proto",
+        "qpc/v1/channel.proto",
+        "qpc/v1/user.proto",
+        "qpc/v1/blob.proto",
+        "qpc/v1/device.proto",
+        "qpc/v1/p2p.proto",
+        "qpc/v1/federation.proto",
+        "qpc/v1/push.proto",
+        "qpc/v1/group.proto",
+        "qpc/v1/moderation.proto",
+        "qpc/v1/recovery.proto",
+    ];
+
+    let full_paths: Vec<PathBuf> = proto_files.iter().map(|f| proto_dir.join(f)).collect();
+
+    for path in &full_paths {
+        println!("cargo:rerun-if-changed={}", path.display());
+    }
+
+    prost_build::Config::new()
+        .out_dir(PathBuf::from(env::var("OUT_DIR").expect("OUT_DIR")))
+        .compile_protos(&full_paths, &[&proto_dir])
+        .expect("prost compile_protos failed");
+}