T6: Implementation Source Index

Scope

• Purpose: Map every implementation source file to its specification provenance (stage brief, SPECTRE spec, SHACHI pattern)
• Why: STAGE3_INDEX T1–T5 cover specification documents; T6 bridges spec → implementation
• Files: All .c/.h in src/d3tui/ and root-level entry points (src/main.c, src/d3tui_main.c, src/sh4math_stubs.c)