Retitle STR-016 archival notes

docs/modernization/debt.md

@@ -401,8 +401,8 @@ agent or engineer to remove them without reconstructing context from chat.
   shrinking the helper API mismatch while `Canvas::draw_merge_branch_orchestration()`
   still owns the remaining branch orchestration.
 - 2026-06-13: `STR-016` completed in `b9ed78e1`. The per-layer composite block
-  moved out of `Canvas::draw_merge()`, and the helper-shape cleanup is
-  recorded here as completed historical context.
+  moved out of `Canvas::draw_merge()`; this line records the completed
+  extraction.
 - 2026-06-15: `DEBT-0036` was narrowed again. `Canvas::draw_merge_branch_orchestration()`
   now drops the unused `draw_checkerboard` parameter from the internal branch
   wrapper, and `Canvas::draw_merge_temporary_paint_branch()` now drops the

docs/modernization/roadmap.md

@@ -3236,9 +3236,8 @@ Results:
   color through framebuffer fetch or must copy the destination texture before
   the legacy OpenGL blend draw.
 - `STR-016` completed on 2026-06-13 in `b9ed78e1`; the per-layer composite
-  block moved out of `Canvas::draw_merge()`, and the follow-on
-  `draw_checkerboard`/helper-shape cleanup is archived as `DEBT-0036`
-  reduction only.
+  block moved out of `Canvas::draw_merge()`, and the remaining
+  `draw_checkerboard`/helper-shape cleanup is archived under `DEBT-0036`.
 - `Canvas::draw_merge_branch_orchestration()` and
   `Canvas::draw_merge_temporary_paint_branch()` later kept narrowing
   `DEBT-0036`, and this note remains archival context for the completed