Add process-scoped SQLite telemetry (#22154)

## Summary
- add SQLite init, backfill-gate, and fallback telemetry without
introducing a cross-cutting state-db access wrapper
- install one process-scoped telemetry sink after OTEL startup and let
low-level state/rollout paths emit through it directly
- add process-start metrics for the process owners that initialize
SQLite

---------

Co-authored-by: Owen Lin <owen@openai.com>

codex-rs/app-server/src/message_processor.rs

@@ -65,7 +65,6 @@ use codex_arg0::Arg0DispatchPaths;
 use codex_chatgpt::workspace_settings;
 use codex_core::ThreadManager;
 use codex_core::config::Config;
-use codex_core::thread_store_from_config;
 use codex_exec_server::EnvironmentManager;
 use codex_feedback::CodexFeedback;
 use codex_login::AuthManager;
@@ -298,7 +297,7 @@ impl MessageProcessor {
         // The thread store is intentionally process-scoped. Config reloads can
         // affect per-thread behavior, but they must not move newly started,
         // resumed, or forked threads to a different persistence backend/root.
-        let thread_store = thread_store_from_config(config.as_ref(), state_db.clone());
+        let thread_store = codex_core::thread_store_from_config(config.as_ref(), state_db.clone());
         let thread_manager = Arc::new(ThreadManager::new(
             config.as_ref(),
             auth_manager.clone(),