[codex] add current time reminder delivery mode config (#30031)

```python
delivery_mode = "any_inference" # default
delivery_mode = "after_user_or_tool_output" # new mode
``` 

## Validation
- just test -p codex-core load_config_resolves_current_time_reminder
- just test -p codex-core
lock_contains_prompts_and_materializes_features

codex-rs/features/src/feature_configs.rs

@@ -141,6 +141,17 @@ pub enum CurrentTimeSource {
     External,
 }
 
+/// Which inference boundaries may receive current-time reminders.
+#[derive(Serialize, Deserialize, Debug, Clone, Copy, Default, PartialEq, Eq, JsonSchema)]
+#[serde(rename_all = "snake_case")]
+pub enum CurrentTimeReminderDeliveryMode {
+    /// Allow a reminder before any inference request once the interval is due.
+    #[default]
+    AnyInference,
+    /// Allow reminders after user input or tool output; new context windows still force one.
+    AfterUserOrToolOutput,
+}
+
 #[derive(Serialize, Deserialize, Debug, Clone, Default, PartialEq, Eq, JsonSchema)]
 #[serde(deny_unknown_fields)]
 pub struct CurrentTimeReminderConfigToml {
@@ -150,6 +161,8 @@ pub struct CurrentTimeReminderConfigToml {
     pub reminder_interval_seconds: Option<u64>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub clock_source: Option<CurrentTimeSource>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub delivery_mode: Option<CurrentTimeReminderDeliveryMode>,
     /// Expose the input-interruptible `clock.sleep` tool.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub sleep_tool: Option<bool>,

codex-rs/features/src/lib.rs

@@ -18,6 +18,7 @@ mod feature_configs;
 mod legacy;
 pub use feature_configs::CodeModeConfigToml;
 pub use feature_configs::CurrentTimeReminderConfigToml;
+pub use feature_configs::CurrentTimeReminderDeliveryMode;
 pub use feature_configs::CurrentTimeSource;
 pub use feature_configs::MultiAgentV2ConfigToml;
 pub use feature_configs::NetworkProxyConfigToml;