feat: Update browser tab title to show chart name in Explore view

[Praise-creator]

SUMMARY

Updates the browser tab title to display the chart name when viewing charts in Explore view.

Changes

• Added useEffect hook in ExploreViewContainer to update document.title when sliceName changes
• Title resets to "Superset" on component unmount
• Follows same pattern as DashboardPage.tsx

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

Open Superset and navigate to an existing chart in Explore view
Verify the browser tab title displays the chart name
Open a different chart in a new tab
Verify the new tab shows the second chart's name
Navigate away from the chart (e.g., go to the home page)
Verify the tab title resets to "Superset"
Open a dashboard and verify its title appears in the tab
Navigate away from the dashboard
Verify the tab title resets to "Superset"

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

Fixes #20