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/tui/src/app/tests.rs

@@ -4844,6 +4844,7 @@ fn token_usage_notification(
                 total_tokens: 10,
                 input_tokens: 4,
                 cached_input_tokens: 1,
+                cache_write_input_tokens: 0,
                 output_tokens: 5,
                 reasoning_output_tokens: 0,
             },
@@ -4851,6 +4852,7 @@ fn token_usage_notification(
                 total_tokens: 10,
                 input_tokens: 4,
                 cached_input_tokens: 1,
+                cache_write_input_tokens: 0,
                 output_tokens: 5,
                 reasoning_output_tokens: 0,
             },

codex-rs/tui/src/chatwidget/tests/helpers.rs

@@ -375,6 +375,7 @@ fn token_usage_breakdown(usage: TokenUsage) -> codex_app_server_protocol::TokenU
         total_tokens: usage.total_tokens,
         input_tokens: usage.input_tokens,
         cached_input_tokens: usage.cached_input_tokens,
+        cache_write_input_tokens: 0,
         output_tokens: usage.output_tokens,
         reasoning_output_tokens: usage.reasoning_output_tokens,
     }