Track prompt cache write token usage (#33454)

## What changed

- Parse `cache_write_tokens` from response input token details and carry it through token usage aggregation.
- Expose `cache_write_input_tokens` in protocol, app-server, exec, and TypeScript SDK usage events, defaulting it to zero for compatibility with older payloads.
- Report cache-write usage in analytics, metrics, traces, and rollout data alongside existing cache-read usage.

## Testing

- Add coverage for response parsing, usage event output, aggregation, analytics, metrics, and telemetry fields.

GitOrigin-RevId: 634e4fbe3086a8923c0ee13b622573e7d9d221bd

codex-rs/ext/goal/src/accounting.rs

@@ -316,6 +316,9 @@ fn token_delta_since_last_accounting(last: &TokenUsage, current: &TokenUsage) ->
         cached_input_tokens: current
             .cached_input_tokens
             .saturating_sub(last.cached_input_tokens),
+        cache_write_input_tokens: current
+            .cache_write_input_tokens
+            .saturating_sub(last.cache_write_input_tokens),
         output_tokens: current.output_tokens.saturating_sub(last.output_tokens),
         reasoning_output_tokens: current
             .reasoning_output_tokens