Harden CI with Release builds, warnings-as-errors, sanitizers, and fuzzing

[AlexJuca]

Context

Current CI builds Debug on macOS and Ubuntu and runs the existing CTest suite. For production readiness, CI should catch undefined behavior, memory errors, warning regressions, and parser bugs before merge.

Relevant code:

• .github/workflows/cmake-multi-platform.yml
• CMakeLists.txt

Scope

• Add Release build coverage in CI.
• Add strict warnings (-Wall -Wextra -Wpedantic) and a warnings-as-errors CI profile.
• Add sanitizer jobs: ASan, UBSan, and LeakSanitizer where supported.
• Make static analysis actionable: fail CI on high-severity findings or publish clear SARIF/artifacts.
• Add fuzzing harnesses for protocol frame parsing and command handlers, ideally runnable locally and in CI.
• Fix CMake standard configuration so C23 is actually applied consistently.

Acceptance criteria

• CI runs Debug and Release builds on Linux and macOS.
• Sanitizer jobs pass on the test suite.
• Warning regressions fail at least one CI job.
• Protocol fuzz target exists and can run in a bounded CI mode.
• CodeChecker/static-analysis output is generated from the correct path and not silently ignored for severe findings.