Add support codes API and portal server changes

- support_codes.rs: 6-digit code management
- main.rs: Portal routes, static file serving, AppState
- relay/mod.rs: Updated for AppState
- Cargo.toml: Added rand, tower-http fs feature

Generated with Claude Code

server/Cargo.toml

@@ -12,7 +12,7 @@ tokio = { version = "1", features = ["full", "sync", "time", "rt-multi-thread",
 # Web framework
 axum = { version = "0.7", features = ["ws", "macros"] }
 tower = "0.5"
-tower-http = { version = "0.6", features = ["cors", "trace", "compression-gzip"] }
+tower-http = { version = "0.6", features = ["cors", "trace", "compression-gzip", "fs"] }
 
 # WebSocket
 futures-util = "0.3"
@@ -52,6 +52,7 @@ uuid = { version = "1", features = ["v4", "serde"] }
 
 # Time
 chrono = { version = "0.4", features = ["serde"] }
+rand = "0.8"
 
 [build-dependencies]
 prost-build = "0.13"