Update Lyte docs for current syntax

[jersmi7]

Summary

• Rename the user-facing docs to docs/quickstart.md and docs/language-guide.md
• Refresh the guides for current Lyte syntax and Audulus DSP behavior, including semicolon separators, numeric literal suffixes, float modulo, inline-if guidance, macros, and slice precondition notes
• Link the renamed docs from README.md and update the stale regression-doc reference

Validation

• git diff --check HEAD~1..HEAD
• confirmed no remaining references to docs/lyte-dsp-quickstart.md or docs/tutorial.md