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/012_moderation.sql

@@ -0,0 +1,20 @@
+-- Moderation tables: reports and bans.
+
+CREATE TABLE IF NOT EXISTS reports (
+    id                  INTEGER PRIMARY KEY AUTOINCREMENT,
+    encrypted_report    BLOB NOT NULL,
+    conversation_id     BLOB NOT NULL,
+    reporter_identity   BLOB NOT NULL,
+    created_at          INTEGER NOT NULL DEFAULT (strftime('%s', 'now'))
+);
+
+CREATE INDEX IF NOT EXISTS idx_reports_created ON reports(created_at);
+
+CREATE TABLE IF NOT EXISTS bans (
+    identity_key    BLOB PRIMARY KEY,
+    reason          TEXT NOT NULL DEFAULT '',
+    banned_at       INTEGER NOT NULL DEFAULT (strftime('%s', 'now')),
+    expires_at      INTEGER NOT NULL DEFAULT 0
+);
+
+CREATE INDEX IF NOT EXISTS idx_bans_expires ON bans(expires_at);