feat: add invite code validity controls

- Add invite code starts/expires fields across contracts, API, Spacetime bindings, and admin UI
- Enforce pending/expired invite code redemption behavior and expose admin status
- Add admin write-operation confirmation guard and documentation
- Add invite code contract/runtime tests

server-rs/crates/module-runtime/tests/invite_code_validity.rs

@@ -0,0 +1,60 @@
+use module_runtime::{
+    RuntimeProfileFieldError, RuntimeProfileInviteCodeSnapshot, RuntimeProfileInviteCodeStatus,
+    build_runtime_profile_invite_code_record, resolve_runtime_profile_invite_code_status,
+    validate_runtime_profile_invite_code_validity_window,
+};
+
+#[test]
+fn invite_code_validity_window_rejects_start_after_expire() {
+    let result = validate_runtime_profile_invite_code_validity_window(Some(20), Some(10));
+
+    assert_eq!(
+        result,
+        Err(RuntimeProfileFieldError::InvalidInviteCodeValidityWindow)
+    );
+}
+
+#[test]
+fn invite_code_validity_window_allows_open_ended_or_equal_boundary() {
+    assert!(validate_runtime_profile_invite_code_validity_window(None, None).is_ok());
+    assert!(validate_runtime_profile_invite_code_validity_window(Some(10), None).is_ok());
+    assert!(validate_runtime_profile_invite_code_validity_window(None, Some(10)).is_ok());
+    assert!(validate_runtime_profile_invite_code_validity_window(Some(10), Some(10)).is_ok());
+}
+
+#[test]
+fn invite_code_status_uses_inclusive_start_and_exclusive_expire_boundary() {
+    assert_eq!(
+        resolve_runtime_profile_invite_code_status(Some(20), None, 19),
+        RuntimeProfileInviteCodeStatus::Pending
+    );
+    assert_eq!(
+        resolve_runtime_profile_invite_code_status(Some(20), Some(30), 20),
+        RuntimeProfileInviteCodeStatus::Active
+    );
+    assert_eq!(
+        resolve_runtime_profile_invite_code_status(Some(20), Some(30), 29),
+        RuntimeProfileInviteCodeStatus::Active
+    );
+    assert_eq!(
+        resolve_runtime_profile_invite_code_status(Some(20), Some(30), 30),
+        RuntimeProfileInviteCodeStatus::Expired
+    );
+}
+
+#[test]
+fn invite_code_record_formats_window_and_status() {
+    let record = build_runtime_profile_invite_code_record(RuntimeProfileInviteCodeSnapshot {
+        user_id: "user-1".to_string(),
+        invite_code: "SY00000001".to_string(),
+        metadata_json: "{}".to_string(),
+        starts_at_micros: Some(0),
+        expires_at_micros: Some(1_000_000),
+        created_at_micros: 0,
+        updated_at_micros: 1_000_000,
+    });
+
+    assert_eq!(record.starts_at.as_deref(), Some("1970-01-01T00:00:00Z"));
+    assert_eq!(record.expires_at.as_deref(), Some("1970-01-01T00:00:01Z"));
+    assert_eq!(record.status, RuntimeProfileInviteCodeStatus::Expired);
+}