feat: implement account recovery with encrypted backup bundles

Add recovery code generation (8 codes per setup), Argon2id key derivation,
ChaCha20-Poly1305 encrypted bundles, and server-side zero-knowledge storage.
Each code independently recovers the account. Includes core crypto module,
protobuf service (method IDs 750-752), server domain + handlers, SDK methods,
SQL migration, and CLI commands (/recovery setup, /recovery restore).

crates/quicproquo-proto/build.rs

@@ -51,6 +51,9 @@ fn main() {
         "qpq/v1/p2p.proto",
         "qpq/v1/federation.proto",
         "qpq/v1/push.proto",
+        "qpq/v1/group.proto",
+        "qpq/v1/moderation.proto",
+        "qpq/v1/recovery.proto",
     ];
 
     let full_paths: Vec<PathBuf> = proto_files.iter().map(|f| proto_dir.join(f)).collect();