fix(seasons): derive the FUT web-file base from openfut.cfg, not a lab IP

`STAGING_FUT_BASE` hardcoded `http://10.10.0.120:8110/fut/` into the hook
binary, so the base-supply rewriter only worked on one machine and could not be
merged.

The prefix now comes from the same `openfut.cfg` / `openfut-common` source of
truth as every redirect target: `fut_content_base()` builds
`http://<host>:<fut_content_port>/fut/` from the configured host.
`OpenFutPorts` gains `fut_content` with a named default
(`default_ports::FUT_CONTENT = 8110`) and an optional `fut_content_port=` key,
matching how every other OpenFUT port is already handled. A cfg written before
the key existed still parses and takes the default — failing it would disarm the
network redirect too.

Arming fails SAFE: an absent or unusable config arms nothing and the rewriter
leaves every url exactly as the client built it, rather than pointing it at a
guessed host. This also adds the `openfut-common` dependency to the hook on this
branch; main already has it.

Proof: the cross-built artifact no longer contains the string 10.10.0.120
(previously compiled in), openfut-common is green at 16 tests including the new
config-derived-base and backward-compatibility cases, and the launcher builds.

openfut-common/src/lib.rs

@@ -53,6 +53,12 @@ pub mod default_ports {
     pub const BLAZE_REDIRECTOR: u16 = 42127;
     /// OpenFUT FIFA 17 Blaze main listener.
     pub const BLAZE_MAIN: u16 = 42130;
+    /// OpenFUT FUT web-file (CDN) content server. Unlike the others this is not
+    /// an EA redirect target: the client never dials it directly, because its
+    /// `RS4::ServerSettings` CDN base arrives EMPTY in the emulator. The hook
+    /// supplies the missing `<base>/fut/` prefix, and the base is built from the
+    /// configured server host plus this port.
+    pub const FUT_CONTENT: u16 = 8110;
 }
 
 /// OpenFUT destination ports. Each field is where an intercepted EA source port
@@ -66,6 +72,9 @@ pub struct OpenFutPorts {
     pub blaze_redirector: u16,
     /// Destination for EA :42127 traffic (Blaze main).
     pub blaze_main: u16,
+    /// FUT web-file content server. Not a redirect destination — see
+    /// [`default_ports::FUT_CONTENT`].
+    pub fut_content: u16,
 }
 
 impl Default for OpenFutPorts {
@@ -74,6 +83,7 @@ impl Default for OpenFutPorts {
             https: default_ports::HTTPS,
             blaze_redirector: default_ports::BLAZE_REDIRECTOR,
             blaze_main: default_ports::BLAZE_MAIN,
+            fut_content: default_ports::FUT_CONTENT,
         }
     }
 }
@@ -209,6 +219,7 @@ impl ServerConfig {
                 "https_port" => ports.https = parse_port(value)?,
                 "blaze_redirector_port" => ports.blaze_redirector = parse_port(value)?,
                 "blaze_main_port" => ports.blaze_main = parse_port(value)?,
+                "fut_content_port" => ports.fut_content = parse_port(value)?,
                 other => {
                     return Err(ConfigError::MalformedConfig(format!(
                         "line {}: unknown key '{other}'",
@@ -225,8 +236,27 @@ impl ServerConfig {
     /// Serialize to the structured `openfut.cfg` format.
     pub fn to_cfg_string(&self) -> String {
         format!(
-            "host={}\nhttps_port={}\nblaze_redirector_port={}\nblaze_main_port={}\n",
-            self.host, self.ports.https, self.ports.blaze_redirector, self.ports.blaze_main
+            "host={}\nhttps_port={}\nblaze_redirector_port={}\nblaze_main_port={}\nfut_content_port={}\n",
+            self.host,
+            self.ports.https,
+            self.ports.blaze_redirector,
+            self.ports.blaze_main,
+            self.ports.fut_content
+        )
+    }
+
+    /// Base URL the FUT web-file (CDN) prefix is built from, e.g.
+    /// `http://10.10.0.120:8110/fut/`.
+    ///
+    /// The client's `RS4::ServerSettings` CDN base arrives EMPTY in the emulator,
+    /// so FUT web-file urls reach the download entry point as bare relative paths
+    /// and fail. The hook supplies this prefix. Built from the SAME configured
+    /// host as every other redirect, so a lab address is never compiled in.
+    pub fn fut_content_base(&self) -> String {
+        format!(
+            "http://{}:{}/fut/",
+            self.host.trim(),
+            self.ports.fut_content
         )
     }
 
@@ -414,12 +444,36 @@ mod tests {
                 https: 8443,
                 blaze_redirector: 10041,
                 blaze_main: 42127,
+                fut_content: 8110,
             },
         };
         let s = c.to_cfg_string();
         assert_eq!(ServerConfig::parse(&s).unwrap(), c);
     }
 
+    /// The FUT web-file prefix follows the CONFIGURED server, so no lab address
+    /// is ever compiled into the hook.
+    #[test]
+    fn fut_content_base_follows_the_configured_host() {
+        let c = ServerConfig::parse("host=192.168.1.50\n").unwrap();
+        assert_eq!(c.fut_content_base(), "http://192.168.1.50:8110/fut/");
+
+        let c = ServerConfig::parse("host=fut.mylan.home\nfut_content_port=9110\n").unwrap();
+        assert_eq!(c.fut_content_base(), "http://fut.mylan.home:9110/fut/");
+    }
+
+    /// A cfg written before `fut_content_port` existed must still parse, taking
+    /// the default rather than failing the whole config (which would disarm the
+    /// network redirect too).
+    #[test]
+    fn cfg_without_content_port_takes_the_default() {
+        let c = ServerConfig::parse(
+            "host=10.0.0.5\nhttps_port=8443\nblaze_redirector_port=42127\nblaze_main_port=42130\n",
+        )
+        .unwrap();
+        assert_eq!(c.ports.fut_content, default_ports::FUT_CONTENT);
+    }
+
     #[test]
     fn configured_ipv4_becomes_correct_sockaddr() {
         // Resolve an IPv4 literal and confirm the sin_addr value.