Trim trailing tabs as whitespace in trimtrailingspace

[rainman74]

Motivation

• After previous safety fixes removed a crash path, trailing whitespace still remained when lines ended with tabs, so trimtrailingspace must treat \t as removable whitespace in addition to space.

Description

• Updated SRC/NPPTextFX.cpp in trimtrailingspace to change the backward-trim predicate from checking only ' ' to checking (' ' || '\t'), so trailing horizontal tabs are removed along with spaces.

Testing

• Applied and verified the one-line change with nl -ba SRC/NPPTextFX.cpp | sed -n '3672,3681p', git diff --stat, and committed the change; those checks succeeded.
• No Notepad++/Scintilla runtime tests were available in this environment, so behavioral runtime validation was not performed.

---

Codex Task