fix: explore filters break when the explore's metrics_view differs in case from the resource name

[nishantmonu51]

Explore dashboards lose all filtering when the explore's metrics_view value is written in a different case than the metrics view resource name. Resource names are case-insensitive in the runtime, so the explore reconciles and renders, but on the frontend clicking a leaderboard value does nothing and the + filter menu shows "No results found". Introduced by the unified expression filter refactor in #9746 (shipped in v0.90.0).

• MetricsViewsProvider matched the metrics view against the resource list with a case-sensitive comparison, so the provider exposed no dimensions or measures. It now resolves the name case-insensitively while keeping its maps keyed by the requested name.
• ExploreDashboardConfigProvider named the metrics view by the explore's reference, while the explore routes and Dashboard.svelte use the resource's own name from the GetExplore response. The filter expression ended up keyed under a name the dashboard never read, so once the chip appeared the queries still ran unfiltered. The provider now uses the resource name.
• DashboardFetchMocks.mockMetricsExplore takes an optional metrics view resource name so tests can model the mismatch the way the runtime returns it.

Steps to reproduce

1. In any project, name a metrics view file with mixed case, for example AUction_metrics.yaml.
2. In an explore YAML, reference it in lowercase: metrics_view: auction_metrics.
3. Open the explore. It loads and shows data.
4. Click a value in any leaderboard, or open the + filter menu. Before this fix nothing gets filtered and the menu is empty.

Checklist:

• Covered by tests
• Ran it and it works as intended
• Reviewed the diff before requesting a review
• Checked for unhandled edge cases
• Linked the issues it closes
• Checked if the docs need to be updated. If so, create a separate Linear DOCS issue
• Intend to cherry-pick into the release branch
• I'm proud of this work!