Add URL extraction utility with tests and enable clang-tidy check profiling

[MisterVVP]

Motivation

• Provide a single, robust implementation for extracting and normalizing URL target paths used across examples and tests.
• Support different suffix policies (path, query, fragment) to avoid ad-hoc parsing in call sites.
• Improve static-analysis observability by storing a clang-tidy check profile for later inspection.

Description

• Add include/a2a/core/url_utils.h which implements ExtractTargetPath and UrlSuffixPolicy to normalize URL targets and preserve optional query/fragment suffixes.
• Update examples/example_support.h to use core::ExtractTargetPath instead of the previous local UrlToTarget implementation.
• Add unit tests tests/unit/url_utils_test.cpp and register url_utils_test in tests/CMakeLists.txt, and update tests/unit/examples_support_test.cpp to reflect normalized behavior.
• Modify scripts/run_clang_tidy.sh to enable --enable-check-profile and write the profile to ${CLANG_TIDY_CHECK_PROFILE_FILE} (default under the build dir).

Testing

• Ran the new url_utils_test which verifies absolute URLs, no-scheme inputs, suffix policies, and default-path behavior, and it succeeded.
• Ran the updated examples_support_test which validates the normalized target extraction and executor flows, and it succeeded.
• Ran the project unit test suite via CTest (tests discovered with gtest_discover_tests) and all tests passed; additionally scripts/run_clang_tidy.sh was executed and successfully produced a clang-tidy check profile file.

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Codex Task