docs: record conservative non-TP3 corpus cleanup

Remove the SWAG/FreePascal/Delphi tree, unit/uses/FPC/Delphi .pas files, and
archives whose Pascal contents are entirely non-TP3.  Mixed archives such as
pascsrc.zip are kept because they still contain the 44 compiling TP3 examples.

Corpus is now 106 .pas files (44 compile) instead of 4,919 (49 compile).

CORPUS-TEST.md

@@ -61,3 +61,23 @@ Delphi units; only 5 compile.
 The 49 clean files are useful smoke material, but the corpus is intentionally
 not wired into `run_all.sh`: it lives outside the repository and most of it is
 outside the TP3 language subset.
+
+## Conservative cleanup
+
+The obvious non-TP3 material was removed:
+
+- the whole `Dezip/swag-pascal-master` tree and its
+  `swag-pascal-master.zip`;
+- 390 `.pas` files outside that tree that declare `unit`, use `uses`, or carry
+  FreePascal/Delphi markers;
+- 29 zip archives whose Pascal entries were **all** marked in that way.
+
+Mixed archives — including `pascsrc.zip`, which also contains the 44 compiling
+TP3 examples — were deliberately kept.
+
+Before cleanup: **6,810 files**, **4,919 `.pas`**, **907 zips**.
+After cleanup: **1,779 files**, **106 `.pas`**, **871 zips**.
+
+The remaining 106 Pascal files compile as **44 OK / 62 errors**; the errors are
+TP3-feature gaps such as `Word`, `LongInt`, `absolute`, `Printer`/`Dos`, and the
+missing include files, not the unit/Delphi noise.