fix(hooks): after-write dedups its channel files; prior-art tests follow the extractor and skip list into scribe_defs.sh (#2901)

Run 4240: two pre-write hook tests pinned the skip case and scribe_defs()
inside scribe_prior_art.sh, which moved to the shared library; the after-write
test saw the same derive key appended once per changed file. Keep each token
once (sort -u after the appends) and point the pins at the library.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

plugin/hooks/scribe_after_write.sh

@@ -187,6 +187,11 @@ while IFS= read -r rel_path; do
         printf '%s' "$body" | jq -r '((.note_ids // []) - (.sync_note_ids // []))[]?' 2>/dev/null >> "$idfile" || true
         printf '%s' "$body" | jq -r '(.sync_note_ids // [])[]?' 2>/dev/null >> "$syncfile" || true
         printf '%s' "$body" | jq -r '(.derive_keys // [])[]?' 2>/dev/null >> "$derivefile" || true
+        # Several files in one call may name the same family: keep each
+        # token once, so the next request's exclude list stays exact.
+        for f in "$idfile" "$syncfile" "$derivefile"; do
+          [ -s "$f" ] && { sort -u -o "$f" "$f" 2>/dev/null || true; }
+        done
       fi
     fi
   fi