chore: Add UI linter back (#3230)

# What does this PR do?

1. Adds `scripts/run-ui-linter.sh`
- Light script that checks whether `node_modules`,`eslint`, and
`prettier` exist before running linter
- When I introduced [the linter for the
UI](https://github.com/llamastack/llama-stack/pull/3156/files#diff-63a9c44a44acf85fea213a857769990937107cf072831e1a26808cfde9d096b9)
it forced the UI linter on all users, the small `node_modules` check
means that only users that have installed the UI locally (since
`node_modules` is in the gitignore) will actually end up having this
run. Additionally this does not do any install and just runs the
existing linter/prettier as requested by @mattf
2. Updates `.github/workflows/pre-commit.yml` to run CI again
- When I introduced the UI linter in the CI [in this
PR](https://github.com/llamastack/llama-stack/pull/3191) a failure
occurred because dependabot needed to be updated to also bump the
`package-lock.json` which was done [in this
PR](https://github.com/llamastack/llama-stack/pull/3212). All of this to
say, we shouldn't observe failures from dependabot again.
3. Updates `.pre-commit-config.yaml`
    - Calls `scripts/run-ui-linter.sh`

## AI Assistance Notice
I used Copilot minimally. 

## Test Plan
As
[requested](https://github.com/llamastack/llama-stack/pull/3207#discussion_r2288004872)
by @mattf I ran this after removing all of my `node_modules` and the
linter passed.

Signed-off-by: Francisco Javier Arceo <farceo@redhat.com>

.pre-commit-config.yaml

@@ -146,31 +146,13 @@ repos:
         pass_filenames: false
         require_serial: true
         files: ^.github/workflows/.*$
-      # ui-prettier and ui-eslint are disabled until we can avoid `npm ci`, which is slow and may fail -
-      #   npm error `npm ci` can only install packages when your package.json and package-lock.json or npm-shrinkwrap.json are in sync. Please update your lock file with `npm install` before continuing.
-      #   npm error Invalid: lock file's llama-stack-client@0.2.17 does not satisfy llama-stack-client@0.2.18
-      # and until we have infra for installing prettier and next via npm -
-      #   Lint UI code with ESLint.....................................................Failed
-      #   - hook id: ui-eslint
-      #   - exit code: 127
-      #   > ui@0.1.0 lint
-      #   > next lint --fix --quiet
-      #   sh: line 1: next: command not found
-      #
-      # - id: ui-prettier
-      #   name: Format UI code with Prettier
-      #   entry: bash -c 'cd llama_stack/ui && npm ci && npm run format'
-      #   language: system
-      #   files: ^llama_stack/ui/.*\.(ts|tsx)$
-      #   pass_filenames: false
-      #   require_serial: true
-      # - id: ui-eslint
-      #   name: Lint UI code with ESLint
-      #   entry: bash -c 'cd llama_stack/ui && npm run lint -- --fix --quiet'
-      #   language: system
-      #   files: ^llama_stack/ui/.*\.(ts|tsx)$
-      #   pass_filenames: false
-      #   require_serial: true
+      - id: ui-linter
+        name: Format & Lint UI
+        entry: bash ./scripts/run-ui-linter.sh
+        language: system
+        files: ^llama_stack/ui/.*\.(ts|tsx)$
+        pass_filenames: false
+        require_serial: true
 
       - id: check-log-usage
         name: Ensure 'llama_stack.log' usage for logging