fix(core): split WIRE_VERSION from ABI_VERSION — new clients locked out of every deployed host

ABI_VERSION was doing double duty: the embeddable C surface AND the punktfunk/1
Hello/Welcome version that hosts equality-check. The WoL feature's v3 bump added
a client-local FFI function without changing a single wire byte — and every new
client started refusing against every deployed host ("ABI mismatch: client 3
host 2", observed live Deck → Bazzite). The wire now carries its own
WIRE_VERSION (still 2); ABI_VERSION stays 3 for the C header and the mgmt API's
informational field. Bump WIRE_VERSION only when the handshake/planes actually
change incompatibly.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

clients/probe/src/main.rs

@@ -412,7 +412,7 @@ async fn session(args: Args) -> Result<()> {
     io::write_msg(
         &mut send,
         &Hello {
-            abi_version: punktfunk_core::ABI_VERSION,
+            abi_version: punktfunk_core::WIRE_VERSION,
             mode: args.mode,
             compositor: args.compositor,
             gamepad: args.gamepad,