feat: persist explore chart settings in URL state

[djbarnwal]

Currently, the Dynamic Y-Axis Scale and Always-On Line Chart settings in Explore Dashboards are ephemeral local component state. When a user configures these options and shares the dashboard URL, recipients see the default view instead of the intended configuration.

This PR promotes dynamicYAxisScale and forceLineChart from local component state in MetricsTimeSeriesCharts.svelte to the ExploreState store and persists them in the URL as dyn_y and line_chart params. The full established pipeline is used: proto ExplorePreset → URL → V1ExplorePreset → ExploreState round-trip.

• Added chart_dynamic_y_axis and chart_force_line fields to the proto ExplorePreset message
• Registered params as view-specific for Explore and TDD views (not Pivot), with cross-view preservation
• Default behavior unchanged when settings are absent from the URL

https://linear.app/rilldata/issue/APP-806/add-dynamic-y-axis-scale-and-always-line-chart-configs-as-part-of

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!