Mockingboard support and small enhancements

Changes Since V2.11

This update builds on the V2.11 release with a mix of emulator improvements, assembler enhancements, audio work, and usability fixes.

Highlights

• Added Mockingboard support, including ongoing performance and fidelity improvements.
• Reworked Mockingboard audio timing and mixing for better sound quality and lower overhead.
• All Mockingboard files were created using agentic programming with Codex.
• Introduced LUT-driven DHGR rendering.
• Improved Apple ][+ and //e behavior with fixes for I/O, 80-column handling, and SmartPort autostart on Apple ][+.
• Added double-click support in key UI dialogs for expected file and symbol selection.

Assembler Updates

• Added named .scope support so scopes can define output targets such in files or banks.
• Documented named scopes.
• Allowed .include inside control flow.
• Added scoped forward lookup support.
• Fixed scope and target closing behavior.
• Added a ProDOS loader target to the MMINER sample.

Audio Work (done by Codex)

• Added initial Mockingboard support.
• Optimized Mockingboard overhead.
• Changed VIA timer evaluation to be lazy/on-demand.
• Added and refactored rt_audio_update.
• Cleaned up general audio handling.
• Improved Mockingboard audio fidelity.

UI and Workflow

• Added double-click activation in the file browser.
• Added double-click activation in symbol lookup.
• Included a few documentation and sample updates alongside the feature work.