Fix Garage TOML config: move RPC settings to root level

Garage v2.x expects rpc_bind_addr, rpc_secret_file, and bootstrap_peers
at the root level of the TOML config, not inside a [rpc] section.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

templates/compose/garage.yaml

@@ -35,8 +35,7 @@ services:
           compression_level = 1
           block_size = "1M"
 
-          [rpc]
-          bind_addr = "[::]:3901"
+          rpc_bind_addr = "[::]:3901"
           rpc_secret_file = "env:GARAGE_RPC_SECRET"
           bootstrap_peers = []