fix: cache repeated PHP and pkg-config queries

[vencakrecl]

Repeated pie install calls for already-installed extensions currently launch PHP and pkg-config hundreds of times. On macOS with Homebrew PHP 8.4.26 ARM64, the direct command in #758 took 46.19 seconds despite requiring no extension builds or updates.

Cache target-PHP query output per PhpBinaryPath instance and share pkg-config results across the platform repositories created for that target. Cache successful and missing-library queries, with the environment included in the pkg-config key. Refresh runtime information before extension verification and around install/uninstall operations, including failure paths; invalidate dependency information after attempted system-package installation.

Fixes #758.

Validation

• Benchmarked a temporary copy of the installed PIE 1.5.1 PHAR with the patch, invoking PIE directly: 46.19 seconds → 5.30 seconds. All seven extensions remained already installed and verified.
• Instrumented subprocess counts: 114 → 8 PHP launches, 810 → 54 pkg-config launches.
• 67 affected unit tests completed with 141 assertions; 9 tests skipped for platform requirements. Additional cache regression coverage verifies runtime refresh, target isolation, missing-library caching, explicit invalidation, and environment changes.
• 21 dependency resolver tests passed with 38 assertions when run with network access.
• PHPStan and coding-standard checks passed. Tests/static analysis ran on macOS with PHP 8.5.11; the benchmark used PHP 8.4.26.
• The complete unit suite was attempted, but did not pass in this environment: Packagist requests were blocked by the sandbox and sudo tests required an interactive terminal. The dependency resolver tests were subsequently rerun successfully with network access. Linux/Windows execution and real extension installation/removal have not been validated locally.

PR submitter checklist

• I have read CONTRIBUTING.md
• I discussed this bug with the maintainers in Slow no-op installs on macOS: repeated PHP and pkg-config subprocesses #758 (the report is open; maintainer discussion is pending)
• I have added appropriate tests
• I confirm that I have the right to submit this under the project's open source licence