Add redis_calls metric for persistent object cache integration

[Copilot]

Persistent object cache plugins like WP Redis expose $wp_object_cache->redis_calls (an associative array of Redis command → count), but wp profile had no way to surface this data.

Changes

• src/Logger.php — adds $redis_calls public property; start() captures array_sum($wp_object_cache->redis_calls) as an offset, stop() computes and stores the delta. Gracefully no-ops when redis_calls is absent (default WP object cache).
• src/Profiler.php — adds $tick_redis_calls_offset for tick-based (function-level) profiling; mirrors the same offset/delta pattern in handle_function_tick().
• src/Command.php — adds redis_calls to the $metrics fields for stage, hook, eval, and eval-file subcommands.
• features/profile-eval.feature — two new scenarios: one asserting redis_calls = 0 with the default cache; one using a minimal object-cache.php drop-in that mimics WP Redis's redis_calls tracking to assert the count is correct.

Example output

$ wp profile eval 'wp_cache_set( "foo", "bar" ); wp_cache_get( "foo" ); wp_cache_get( "foo" );' \
    --fields=cache_hits,cache_misses,redis_calls
+------------+--------------+-------------+
| cache_hits | cache_misses | redis_calls |
+------------+--------------+-------------+
| 2          | 0            | 3           |
+------------+--------------+-------------+

Any persistent object cache that stores call counts in $wp_object_cache->redis_calls (WP Redis and compatible plugins) will automatically benefit from this integration.

[codecov]

Codecov Report

❌ Patch coverage is 53.84615% with 12 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/Profiler.php	0.00%	12 Missing ⚠️

📢 Thoughts on this report? Let us know!

[tillkruss]

@copilot instead of redis_calls it might be worth using cache_commands or cache_calls to also support memcached or sqlite later.

[tillkruss]

Each plugin has their own property with slightly different names.

WP Redis: $redis_calls
Redis Object Cache: $cache_calls
Object Cache Pro: metrics()->storeReads + metrics()->storeWrites