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.

sdks/python/quicprochat/wire.py

@@ -0,0 +1,73 @@
+"""v2 wire format: ``[method_id:u16][req_id:u32][len:u32][protobuf]``.
+
+Each RPC is sent over its own QUIC stream.  The response uses the same
+framing on the same stream.
+"""
+
+from __future__ import annotations
+
+import struct
+
+# Header: method_id (u16) + req_id (u32) + length (u32) = 10 bytes.
+HEADER_FMT = "!HII"  # network byte-order: u16 + u32 + u32
+HEADER_SIZE = struct.calcsize(HEADER_FMT)
+
+# Method IDs (mirrors quicproquo-proto/src/lib.rs::method_ids).
+# Auth (100-103)
+OPAQUE_REGISTER_START = 100
+OPAQUE_REGISTER_FINISH = 101
+OPAQUE_LOGIN_START = 102
+OPAQUE_LOGIN_FINISH = 103
+
+# Delivery (200-205)
+ENQUEUE = 200
+FETCH = 201
+FETCH_WAIT = 202
+PEEK = 203
+ACK = 204
+BATCH_ENQUEUE = 205
+
+# Keys (300-304)
+UPLOAD_KEY_PACKAGE = 300
+FETCH_KEY_PACKAGE = 301
+UPLOAD_HYBRID_KEY = 302
+FETCH_HYBRID_KEY = 303
+FETCH_HYBRID_KEYS = 304
+
+# Channel (400)
+CREATE_CHANNEL = 400
+
+# User (500-501)
+RESOLVE_USER = 500
+RESOLVE_IDENTITY = 501
+
+# Blob (600-601)
+UPLOAD_BLOB = 600
+DOWNLOAD_BLOB = 601
+
+# Device (700-702)
+REGISTER_DEVICE = 700
+LIST_DEVICES = 701
+REVOKE_DEVICE = 702
+
+# P2P (800-802)
+PUBLISH_ENDPOINT = 800
+RESOLVE_ENDPOINT = 801
+HEALTH = 802
+
+# Delete account (950)
+DELETE_ACCOUNT = 950
+
+
+def encode_frame(method_id: int, req_id: int, payload: bytes) -> bytes:
+    """Encode a wire frame: header + protobuf payload."""
+    header = struct.pack(HEADER_FMT, method_id, req_id, len(payload))
+    return header + payload
+
+
+def decode_header(data: bytes) -> tuple[int, int, int]:
+    """Decode a wire frame header, returning (method_id, req_id, payload_len)."""
+    if len(data) < HEADER_SIZE:
+        raise ValueError(f"header too short: {len(data)} < {HEADER_SIZE}")
+    method_id, req_id, length = struct.unpack(HEADER_FMT, data[:HEADER_SIZE])
+    return method_id, req_id, length