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-server/migrations/010_blobs.sql

@@ -0,0 +1,15 @@
+CREATE TABLE IF NOT EXISTS blobs (
+    blob_id BLOB PRIMARY KEY,
+    data BLOB NOT NULL,
+    total_size INTEGER NOT NULL,
+    mime_type TEXT NOT NULL DEFAULT '',
+    uploaded_at INTEGER NOT NULL
+);
+CREATE TABLE IF NOT EXISTS blob_staging (
+    blob_hash BLOB NOT NULL,
+    offset INTEGER NOT NULL,
+    chunk BLOB NOT NULL,
+    total_size INTEGER NOT NULL,
+    mime_type TEXT NOT NULL DEFAULT '',
+    PRIMARY KEY (blob_hash, offset)
+);