feat(runner): add signal handling support (SIGINT/SIGTERM)

[usernane]

Summary

Adds signal handling support (SIGINT/SIGTERM) to the CLI library, enabling graceful shutdown and per-command cleanup registration.

Motivation

When a CLI application receives OS signals, PHP terminates immediately with no cleanup opportunity. This is problematic for commands holding locks, temp files, or DB transactions, and for interactive mode running in containers. Closes #45.

Changes

• Added SignalHandler class with register(), remove(), enable(), disable(), isSupported() API
• Added enableSignalHandling(), setSignalHandler(), getSignalHandler(), isShutdownRequested() to Runner
• Added onSignal(), getSignalHandlers(), clearSignalHandlers() to Command
• Default SIGINT handler: exits with code 130 (in interactive mode: interrupts command but keeps app alive)
• Default SIGTERM handler: sets shutdown flag, exits with code 143
• Interactive mode loop checks shutdown flag for clean exit
• Per-command signal handlers auto-removed after command finishes
• Graceful degradation on Windows (no-op when pcntl unavailable)

How to Test / Verify

Unit and integration tests with 100% line coverage on all new code:

• tests/WebFiori/Tests/Cli/SignalHandlerTest.php (13 tests)
• tests/WebFiori/Tests/Cli/SignalIntegrationTest.php (22 tests)

Run: composer test

Breaking Changes and Migration Steps

None. All new functionality is opt-in via enableSignalHandling().

Checklist

• I reviewed my own diff before requesting review
• My commits follow Conventional Commits
• I added/updated tests (or explained why not)
• I updated docs (if needed) Docs Repo
• I ran lint/cs-fixer (if applicable) (composer fix-cs)
• I considered backward compatibility
• I considered security

Related issues

Closes #45

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 97.86223% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.97%. Comparing base (54c6bd6) to head (5b68bfe).
⚠️ Report is 2 commits behind head on dev.

Files with missing lines	Patch %	Lines
WebFiori/Cli/Runner.php	97.67%	9 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                dev      #52      +/-   ##
============================================
+ Coverage     87.72%   87.97%   +0.24%     
+ Complexity     1322     1284      -38     
============================================
  Files            33       34       +1     
  Lines          3610     3693      +83     
============================================
+ Hits           3167     3249      +82     
- Misses          443      444       +1     

Flag	Coverage Δ
php-8.1	?
php-8.2	?
php-8.3	87.97% <97.86%> (+0.24%)	⬆️
php-8.4	?
php-8.5	?

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