fix(eslint): promote 5 clean Vue lint rules to error (#13510)

[Nehant14]

Closes #13510

[fix]

Promotes 5 Vue ESLint rules from warn to error in eslint.config.cjs, now that all existing violations were cleaned up by #13473 and #13479. This prevents new violations of these rules from silently accumulating again.

Technical

Added the following to the **/*.vue / **/*.js rules block in eslint.config.cjs, next to the existing vue/multi-word-component-names entry:

"vue/require-prop-types": "error",
"vue/require-explicit-emits": "error",
"vue/require-default-prop": "error",
"vue/no-v-html": "error",
"vue/no-template-shadow": "error",

These rules previously came from eslint-plugin-vue's flat/recommended config at the warn level, and CI does not fail on warnings — so violations could merge unnoticed. All 5 were already at zero violations on master before this change (confirmed by prior cleanup PRs #13473 and #13479), so this flip is zero-cost today and only affects future PRs.

Per the issue, the other ~25 warn rules in flat/recommended (mostly formatting rules like vue/html-indent) were intentionally not promoted, since they'd add CI friction without meaningful safety value.

Testing

• Ran npm run lint (eslint . + stylelint) on the branch — both exit with code 0, 0 errors, 0 warnings.
• Confirmed via git diff --stat master that only eslint.config.cjs was changed (5 insertions, 0 deletions).
• Confirmed via git grep -n "eslint-disable" $(git diff --name-only master) that no eslint-disable comments were added anywhere to force the pass, per the acceptance criteria.

Screenshot

N/A — config-only change, no UI impact.

Stakeholders

@RayBB

[RayBB]

Thanks very much. This solves it and is great!