Core Rule Set: a Ghost post's or page's canonical URL passes when it names a command or a file (closes #374)

While bodies are read, 932120 refused the canonical URL
`https://example.com/blog/powershell/` and 930120 refused
`https://example.com/blog/.htaccess/`. The new exclusions 900383 and 900384
switch both rules off for `posts.N.canonical_url` under
`/ghost/api/admin/posts/` and `pages.N.canonical_url` under
`/ghost/api/admin/pages/`, as `url` does, and only when the query has no field
of that name. The recorded requests gain the saves the Ghost 6.76.0 admin
sends when those addresses are set in a post's and a page's settings.

Model: opus-5-5

SPEC.md

@@ -1773,6 +1773,10 @@ member. A staff user's address skips them too: `username` when signing in, and
 `email` when creating the first staff user, asking for a password reset or
 saving a profile.
 
+The `canonical_url` of a post or a page skips 930120 and 932120, as `url` does.
+A post's skips them under `/ghost/api/admin/posts/`, and a page's under
+`/ghost/api/admin/pages/`.
+
 The articles carry HTML on purpose. These fields on the Admin API hold them:
 
 - `lexical`, which the editor saves, and `mobiledoc` and `html`, which
@@ -1813,7 +1817,7 @@ fields, on the Admin API:
 (941170 and 941210). Path traversal and SQL injection are still refused in every
 field above. Script injection is too, outside the articles and code injection.
 `; wget http://example.com/x.sh` is still refused in the query fields, the plain
-text and the addresses.
+text, the addresses and the canonical URLs.
 
 Coraza names a staff user's `profile_image` field `json.users.0.profile_image`.
 That name holds `.profile`, a file on the list of system files, so the name