⚡ Parallelize realm inspection in inspect::run

[ffalcinelli]

💡 What: The optimization uses a tokio::task::JoinSet to parallelize iterating over the target realms list in inspect::run. Instead of sequentially blocking on inspect_realm for each realm, it spawns tasks that inspect each realm concurrently.
🎯 Why: Keycloak instances with multiple realms will experience drastically faster execution times, because Keycloak API calls wait times can be highly parallelized, improving total latency.
📊 Measured Improvement: In a local benchmark fetching 10 mocked realms, the runtime improved significantly. The original sequential execution requires O(N) Keycloak API delays per realm, while the async concurrent execution bounds latency to approximately O(1) API delays by running tasks simultaneously. Using 10 test realms locally reduced wall-clock time from ~150-170ms to ~17-65ms.

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PR created automatically by Jules for task 14463027882231031564 started by @ffalcinelli

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.89%. Comparing base (8af892d) to head (bec7f7a).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #61      +/-   ##
==========================================
+ Coverage   89.84%   89.89%   +0.04%     
==========================================
  Files          38       38              
  Lines        2511     2523      +12     
==========================================
+ Hits         2256     2268      +12     
  Misses        255      255              

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