Update detached/empty payload error message in COSE decoder

[Copilot]

• Update error message to "Detached or empty payloads are not supported" in app/src/cose.h
• Update matching test assertions in app/unit-tests/cose_test.cpp
• Remove accidentally committed _codeql_detected_source_root symlink and add to .gitignore
• Fix clang-format issues and verify all CI checks pass (C++ format, Python types/mypy, Python imports/isort, Python format/black, copyright notices, release notes)

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[ivarprudnikov]

@copilot remove file _codeql_detected_source_root‎ from git changes

[Copilot]

@copilot remove file _codeql_detected_source_root‎ from git changes

Done in commit 45ba42b. Removed the _codeql_detected_source_root symlink from git tracking and added it to .gitignore to prevent it from being committed again.

[ivarprudnikov]

@copilot run ./scripts/ci-checks.sh to check for Python type safety issues and attempt to fix them if you can.

[Copilot]

@copilot run ./scripts/ci-checks.sh to check for Python type safety issues and attempt to fix them if you can.

Ran ./scripts/ci-checks.sh — all checks pass in ab95ca3. No Python type safety issues were found (mypy reported "Success: no issues found in 49 source files"). The only issue was a C++ clang-format violation in cose_test.cpp which has been fixed.