feat(sidecar): protocol 12 — POST /titles (phase 17)

One more thin forward: the chat titles each player has earned, as a whole
set the plugin swaps in and BetterChat reads on the chat path. perm.sync's
BetterChat styles and chat.say's delivery and format pass through untouched
like the rest of their bodies. PROTOCOL_VERSION moves to 12.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

sidecar/src/main.rs

@@ -163,8 +163,8 @@ use tracing_subscriber::EnvFilter;
 ///
 /// `docs/rust-link/PROTOCOL.md` is the specification — §8 the read path, §9 identity, §10 the
 /// mirror, §11 configuration, §12 clans, §13 the raid frame, §14 the leases, §15 the world verbs,
-/// §16 the rewards, §17 the map; this constant is one of its four declaration sites.
-pub const PROTOCOL_VERSION: u32 = 11;
+/// §16 the rewards, §17 the map, §18 the optional mods; this constant is one of its four declaration sites.
+pub const PROTOCOL_VERSION: u32 = 12;
 
 fn main() -> anyhow::Result<()> {
     let args = match cli::parse(std::env::args().skip(1)) {