Explicit tests marked with [Explicit] attribute were not being discovered by IDEs like Rider, making them invisible in test explorers and missing the green triangle indicators next to test methods. The issue occurred because the test discovery pipeline was filtering out explicit tests during the discovery phase.

Root Cause:
The TestDiscoveryService.DiscoverTests() method was applying _testFilterService.FilterTests() during discovery, which removed explicit tests from the results sent to IDEs. IDEs need to see ALL tests (including explicit ones) during discovery to display them in test explorers.

Solution:
Separated discovery behavior from execution filtering by:

1. Adding an isForExecution parameter to TestDiscoveryService.DiscoverTests()
2. For discovery requests (isForExecution: false): Return all tests including explicit ones
3. For execution requests (isForExecution: true): Apply normal filtering to exclude explicit tests unless explicitly targeted

Changes:

• TestDiscoveryService.cs: Added overload with isForExecution parameter to control filtering behavior
• TestRequestHandler.cs: Updated discovery requests to use isForExecution: false and run requests to use isForExecution: true

Result:

• ✅ Explicit tests are now discovered by IDEs and visible in test explorers
• ✅ Green triangle indicators appear next to explicit test methods
• ✅ Explicit tests still only execute when explicitly targeted (existing behavior preserved)
• ✅ Regular wildcard filters still exclude explicit tests from execution

The fix is minimal and surgical, maintaining backward compatibility while restoring the expected IDE experience.

Fixes #2946.

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