fix(release): drop body-grep Security grouping, map polish type in cliff

The body=".*security" parser ran before the docs/chore skip rules, so
any commit merely mentioning security in its body landed in the
Security section (e.g. a docs commit and the CalVer->SemVer ci commit).
Real security fixes never reached it — ^fix matches first — so the rule
only ever produced miscategorized entries. Removed.

polish(...) commits had no parser, and git-cliff defaults the group to
the raw type — rendering a stray lowercase "polish" section. Mapped to
Changed.

cliff.toml

@@ -39,7 +39,7 @@ commit_parsers = [
     { message = "^perf", group = "Changed" },
     { message = "^refactor", group = "Changed" },
     { message = "^security", group = "Security" },
-    { body = ".*security", group = "Security" },
+    { message = "^polish", group = "Changed" },
     { body = "BREAKING", group = "Breaking" },
     { footer = "BREAKING.CHANGE", group = "Breaking" },
     { message = "^docs", skip = true },