feat(utas-host): serve GET /squad/active from Core

Migrate the active-squad READ off the Python oracle to the existing Core-backed projector, completing the squad authority (read + write + /squad/list + userMassInfo overlay) on one projector.

- classify: GET /ut/game/<t>/squad/active -> Route::SquadActive. Numeric GET /squad/<n> stays on Python (no Core multi-squad model yet).
- handle_squad_active returns the projector object via user_mass_info_squad(v, persona) — byte-identical to userMassInfo.squad; degrades to an empty overlay on stale/missing/Core-error, never falls back to Python.
- persona: new REQUIRED OPENFUT_PERSONA_ID (non-zero) on HostConfig, injected not baked, must match LSX/Blaze/POW/UTAS identity.
- tests: squad_active parity test; classify updated; README config table + A/B command.

fmt + clippy -D warnings + tests (24 host + adapter) green.

openfut-utas-host/src/config.rs

@@ -23,6 +23,10 @@ pub struct HostConfig {
     /// id). Required: the wire `id` of every owned item is allocated/resolved
     /// here so it survives restart and reverses exactly.
     pub identity_store_path: String,
+    /// The launcher-selected FIFA persona id, injected via `OPENFUT_PERSONA_ID`.
+    /// Required, non-zero: it stamps `personaId` on the Core-backed
+    /// `GET /squad/active`, and must match the persona LSX/Blaze/POW/UTAS use.
+    pub persona_id: i64,
 }
 
 #[derive(Debug)]
@@ -42,6 +46,19 @@ fn required(key: &str) -> Result<String, ConfigError> {
     }
 }
 
+/// Parse a required, non-zero i64 env var. A zero identity id is invalid (the
+/// client rejects a zero persona), so unset/empty/non-integer/zero is a hard error.
+fn required_i64_nonzero(key: &str) -> Result<i64, ConfigError> {
+    let raw = required(key)?;
+    let val: i64 = raw
+        .parse()
+        .map_err(|_| ConfigError(format!("{key} must be an integer, got {raw:?}")))?;
+    if val == 0 {
+        return Err(ConfigError(format!("{key} must be non-zero")));
+    }
+    Ok(val)
+}
+
 impl HostConfig {
     pub fn from_env() -> Result<Self, ConfigError> {
         Ok(HostConfig {
@@ -53,6 +70,7 @@ impl HostConfig {
                 .unwrap_or_else(|_| "fifa17-recon/data/tables".into()),
             catalog_path: required("OPENFUT_FIFA17_CATALOG")?,
             identity_store_path: required("OPENFUT_IDENTITY_STORE")?,
+            persona_id: required_i64_nonzero("OPENFUT_PERSONA_ID")?,
         })
     }
 }