Fix nested process color output

[coisa]

Summary

• restore color-friendly nested process execution without PTY by configuring child process environments and explicit Symfony Console ANSI flags
• add concise process labels and local Symfony-style sections for human-readable queue output
• keep PhpMetrics Composer analysis enabled while excluding nested fixture projects and bounding per-package Packagist lookups so metrics generation does not hang
• suppress repeated nested Composer Xdebug warnings by setting XDEBUG_MODE=off for queued child processes unless coverage needs Xdebug and PCOV is unavailable

Verification

• composer dev-tools metrics -- --target=.dev-tools/tmp-metrics --progress
• composer dev-tools phpdoc -- --fix
• composer dev-tools code-style -- --fix
• composer dev-tools tests -- --filter='(EnvironmentTest|OutputCapabilityDetectorTest|ColorPreservingProcessEnvironmentConfiguratorTest|ProcessQueueTest|OutputFormatLoggerTest|TestsCommandTest|MetricsCommandTest|CodeStyleCommandTest|RefactorCommandTest|DocsCommandTest|PhpDocCommandTest|ReportsCommandTest|StandardsCommandTest|DependenciesCommandTest|WikiCommandTest|FundingCommandTest|SyncCommandTest)'
• composer dev-tools tests -- --filter='(MetricsCommandTest|OutputCapabilityDetectorTest|XdebugDisablingProcessEnvironmentConfigurator|CompositeProcessEnvironmentConfigurator|Extension)'
• composer dev-tools tests -- --filter=XdebugDisablingProcessEnvironmentConfigurator --coverage=.dev-tools/coverage/xdebug-smoke --coverage-summary
• composer dev-tools tests
• composer dev-tools changelog:check
• git diff --check
• GrumPHP pre-commit hook

Notes

• PHP-CS-Fixer still emits its upstream warning when running on PHP 8.5 while the project minimum is PHP 8.3; PHP_CS_FIXER_IGNORE_ENV is deprecated and did not suppress that warning, so this PR avoids adding that env-based workaround.
• A top-level composer dev-tools ... invocation can still print Composer's Xdebug warning before DevTools starts. The new environment policy targets queued child processes, which removes the repeated warnings from orchestrated Composer calls.
• PhpMetrics still performs Composer package enrichment, but nested fixture manifests are excluded and each Packagist socket lookup is bounded defensively at 1 second to keep aggregate workflows under their hook and CI time budgets.
• Colored --pretty-json was intentionally deferred to Support colored pretty JSON and structured tool result payloads #248 so strict --json/--pretty-json output remains parseable JSON while we design structured tool-result payloads.

Closes #239

[github-actions]

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• Docs: https://php-fast-forward.github.io/dev-tools/previews/pr-247/
• Coverage: https://php-fast-forward.github.io/dev-tools/previews/pr-247/coverage/
• Metrics: https://php-fast-forward.github.io/dev-tools/previews/pr-247/metrics/