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.

proto/qpc/v1/keys.proto

@@ -0,0 +1,84 @@
+syntax = "proto3";
+package qpc.v1;
+
+// Key package + hybrid key CRUD (5 methods).
+// Method IDs: 300-304.
+
+message UploadKeyPackageRequest {
+  bytes identity_key = 1;
+  bytes package = 2;
+}
+
+message UploadKeyPackageResponse {
+  bytes fingerprint = 1;
+}
+
+message FetchKeyPackageRequest {
+  bytes identity_key = 1;
+}
+
+message FetchKeyPackageResponse {
+  bytes package = 1;
+}
+
+message UploadHybridKeyRequest {
+  bytes identity_key = 1;
+  bytes hybrid_public_key = 2;
+}
+
+message UploadHybridKeyResponse {}
+
+message FetchHybridKeyRequest {
+  bytes identity_key = 1;
+}
+
+message FetchHybridKeyResponse {
+  bytes hybrid_public_key = 1;
+}
+
+message FetchHybridKeysRequest {
+  repeated bytes identity_keys = 1;
+}
+
+message FetchHybridKeysResponse {
+  repeated bytes keys = 1;
+}
+
+// Key revocation (method ID 510).
+message RevokeKeyRequest {
+  bytes identity_key = 1;
+  string reason = 2; // "compromised", "superseded", "user_revoked"
+}
+
+message RevokeKeyResponse {
+  bool success = 1;
+  uint64 leaf_index = 2; // Index of revocation entry in the KT Merkle log
+}
+
+// Check revocation status (method ID 511).
+message CheckRevocationRequest {
+  bytes identity_key = 1;
+}
+
+message CheckRevocationResponse {
+  bool revoked = 1;
+  string reason = 2;
+  uint64 timestamp_ms = 3;
+}
+
+// KT audit log retrieval (method ID 520).
+message AuditKeyTransparencyRequest {
+  uint64 start = 1;
+  uint64 end = 2; // 0 = up to current size
+}
+
+message AuditKeyTransparencyResponse {
+  repeated LogEntry entries = 1;
+  uint64 tree_size = 2;
+  bytes root = 3;
+}
+
+message LogEntry {
+  uint64 index = 1;
+  bytes leaf_hash = 2;
+}