feat: add complete model constants, fix GPT-5 parameter handling, release prep

test: add Laravel 13 to integration test script

docs: update changelog with ImageContent detail and Laravel 13 support

feat: add Laravel 13 compatibility and update test dependencies

fix: address code review issues and add ImageContent detail parameter

docs: update changelog, README, CLAUDE.md, and add UPGRADING.md for v0.5.0

test: update feature tests to use current model constants

test: update and add unit tests for Engine, extractors, and text loaders

chore: bump PHP requirement to 8.3+ and widen collision constraint

refactor: update ExtractorManager to use nullable model with config fallback

feat: add system prompt support and configurable default model

refactor: modernize Engine with current OpenAI models and unified chat API

test: add coverage tests and fix DOCX MIME routing bug

fix: remove unnecessary use statement for InvalidArgumentException

feat: split test suites so unit tests run fast by default