fix(ci): cover other widely-cited invisible code points in check-unicode-safety

Extend `isDangerousInvisibleCodePoint` with five additional code
points / ranges that are routinely cited in invisible-character
smuggling references but were not in the previous denylist:

- **U+180E** MONGOLIAN VOWEL SEPARATOR. Formerly classified as a
  space separator (Zs) until Unicode 6.3 reclassified it as Cf
  (Format control). Renders as zero-width; widely abused for
  homograph attacks and prompt smuggling.

- **U+115F** HANGUL CHOSEONG FILLER and **U+1160** HANGUL JUNGSEONG
  FILLER. Zero-width fillers used in Korean text shaping. Both are
  cited as common LLM-injection vectors in Korean / multilingual
  threat models.

- **U+2061–U+2064** invisible math operators (FUNCTION APPLICATION,
  INVISIBLE TIMES, INVISIBLE SEPARATOR, INVISIBLE PLUS). Zero-width
  and only meaningful inside math typesetting. No legitimate
  Markdown or source code uses them.

- **U+3164** HANGUL FILLER. Reported in real-world Discord and
  Twitter smuggling incidents; not used in legitimate Korean text.

Reproduced before this commit: a file containing any one of these
code points passed `check-unicode-safety.js` silently.

After this commit each one is reported as
`dangerous-invisible U+<HEX>` and `--write` mode strips it.

Verified by writing 8 single-character probe files
(`probe-0x180E.md`, `probe-0x115F.md`, …) and confirming exit=1 with
each violation listed.

ECC repo self-scan reports only the pre-existing `U+2605` BLACK
STAR warnings (unchanged) and exits with the same status (no new
in-repo violations introduced). Existing 5 unicode-safety tests
still pass; `yarn lint` clean.

Regression coverage for both the previous commit's Tag block fix
and this commit's additions lands in the next commit.

scripts/ci/check-unicode-safety.js

@@ -122,7 +122,23 @@ function isDangerousInvisibleCodePoint(codePoint) {
     // an attacker hides instructions inside ASCII-looking strings (PR
     // bodies, SKILL.md, frontmatter), the LLM consumes the tag bytes,
     // and the human reviewer sees nothing.
-    (codePoint >= 0xE0000 && codePoint <= 0xE007F)
+    (codePoint >= 0xE0000 && codePoint <= 0xE007F) ||
+    // U+180E MONGOLIAN VOWEL SEPARATOR — formerly classified as a space
+    // separator, reclassified as a format control in Unicode 6.3; renders
+    // as zero-width and routinely abused for homograph / smuggling.
+    codePoint === 0x180E ||
+    // U+115F / U+1160 HANGUL CHOSEONG/JUNGSEONG FILLER — zero-width fillers
+    // used in Korean text shaping; abused as invisible characters.
+    codePoint === 0x115F ||
+    codePoint === 0x1160 ||
+    // U+2061–U+2064 invisible math operators (FUNCTION APPLICATION,
+    // INVISIBLE TIMES, INVISIBLE SEPARATOR, INVISIBLE PLUS). Zero-width
+    // and not used outside math typesetting; legitimate Markdown / source
+    // does not contain them.
+    (codePoint >= 0x2061 && codePoint <= 0x2064) ||
+    // U+3164 HANGUL FILLER — zero-width filler reportedly used in Discord
+    // / Twitter smuggling attacks; not used in legitimate Korean text.
+    codePoint === 0x3164
   );
 }