fix(core): Preserve dynamic content in Texts on deepcopy

feat(message): Automatically convert image dicts to Images provider

feat(files): Make Files.update head parameter accept string values

feat(core): Enhance Files provider with head and source tracking

feat(core): Auto-merge consecutive messages with the same role

feat(core): Enable appending text to Texts providers with `+=`

feat(core): Enable message absorption for flexible composition

feat: Implement caching in Message.render for performance

feat: Add `__repr__` to Messages for better inspection

feat(core): Pre-cache static content for immediate rendering

feat(core): Add `newline` parameter to Texts provider

feat: Add strip, lstrip, and rstrip methods to Message

feat: Add Message.has() to check for provider types

feat(core): Ignore None on init and add async render_latest

docs: Add LICENSE file