[PWGUD] Fix cpplint errors

[vkucera]

Fixes errors from the following categories:

• readability/inheritance
• readability/braces
• readability/multiline_comment
• whitespace/newline
• whitespace/empty_if_body
• build/include_what_you_use
• build/header_guard

[github-actions]

O2 linter results: ❌ 0 errors, ⚠️ 196 warnings, 🔕 0 disabled

[alibuild]

Error while checking build/O2Physics/code-check for 728873d at 2026-09-29 17:06:

## sw/BUILD/O2Physics-code-check-latest/log
--
========== List of issues found ==========
++ echo 'Found 1 errors and 113 warnings.'
Found 1 errors and 113 warnings.
++ [[ 1 -gt 0 ]]
++ cat /sw/BUILD/1f13ff11b48431aaed71966d7f313ade85b2dd3a/O2Physics-code-check/errors.txt
PWGUD/Tasks/sgSpectraAnalyzer.cxx:237:9: error: Value stored to 'gapSide' during its initialization is never read [clang-analyzer-deadcode.DeadStores,-warnings-as-errors]
++ [[ 113 -gt 0 ]]
++ cat /sw/BUILD/1f13ff11b48431aaed71966d7f313ade85b2dd3a/O2Physics-code-check/warnings.txt
PWGUD/Tasks/sgFITAnalyzer.cxx:58:8: warning: constructor does not initialize these fields: pdg [cppcoreguidelines-pro-type-member-init]
PWGUD/Tasks/sgFITAnalyzer.cxx:385:5: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays]
PWGUD/Tasks/sgFITAnalyzer.cxx:420:11: warning: implicit conversion 'int' -> 'bool' [readability-implicit-bool-conversion]
PWGUD/Tasks/sgFITAnalyzer.cxx:423:43: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:431:107: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:437:115: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:463:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:465:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:467:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:469:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:471:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:473:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:475:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:477:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:479:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:481:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:483:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:485:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:487:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:489:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:491:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:493:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:495:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:497:26: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:505:38: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:507:38: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:509:28: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:511:34: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:513:35: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:515:23: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:517:28: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:519:34: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:521:35: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:523:23: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:579:11: warning: implicit conversion 'int' -> 'bool' [readability-implicit-bool-conversion]
PWGUD/Tasks/sgFITAnalyzer.cxx:579:17: warning: implicit conversion 'int' -> 'bool' [readability-implicit-bool-conversion]
PWGUD/Tasks/sgFITAnalyzer.cxx:579:20: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:585:21: warning: statement should be inside braces [readability-braces-around-statements]
PWGUD/Tasks/sgFITAnalyzer.cxx:609:11: warning: implicit conversion 'int' -> 'bool' [readability-implicit-bool-conversion]
[0 more errors; see full log]

Full log here.