docs(fix[cli]): ref-link grid-item-cards instead of url-fragment anchors

why: The two grid-item-card blocks in the CLI Reference page used
URL-fragment 🔗 options (`#command`, `#supported-vcs`) with
:link-type: url.  MyST-parser treats `#` inside a directive's
options block as a YAML-style comment, so the fragment was
stripped and 🔗 was left with an empty value.  That produced
five cascading `sphinx-build -W` warnings: two
[myst.directive_comments], two [myst.directive_option] ("Invalid
option value for 'link': None"), and one [design.grid] ("All
children of a 'grid-row' should be 'grid-item'") because the
half-parsed card nodes weren't valid grid-items for sphinx-design
0.7's stricter row-children check.
what:
- Switch both grid-item-cards to :link-type: ref with bare label
  targets (🔗 cli-main, 🔗 cli-supported-vcs).  No `#`
  in the options block -> no MyST comment interpretation -> the
  cards parse cleanly as grid-items and the cascading
  design.grid warning goes away.
- Add a (cli-supported-vcs)= label before the `## Supported VCS`
  heading so the new ref target resolves.  cli-main already
  existed above `## Command`.
- Does not address the remaining "Duplicate ID: usage" critical
  from the manual `## Usage` heading colliding with the
  .. argparse:: directive's built-in Usage section — that lands
  in a separate commit for reviewability.

Author: tony

docs/cli/index.md

@@ -6,14 +6,14 @@
 :gutter: 2 2 3 3
 
 :::{grid-item-card} g
-:link: #command
-:link-type: url
+:link: cli-main
+:link-type: ref
 Proxy to your repo's VCS command.
 :::
 
 :::{grid-item-card} Supported VCS
-:link: #supported-vcs
-:link-type: url
+:link: cli-supported-vcs
+:link-type: ref
 git, svn, and hg detection.
 :::
 
@@ -65,6 +65,8 @@ $ g log --oneline -10
 $ g diff HEAD~1
 ```
 
+(cli-supported-vcs)=
+
 ## Supported VCS
 
 | Directory marker | VCS command |