feat: migrate home dashboard to react scenes

[VikaCep]

Closes #1560

Problem

While all other dashboards use react-scenes, the dashboard displayed in the home page (summary) was still using the old scenes version (no react).

Solution

Migrated the Summary/Home dashboard to @grafana/scenes-react to match the pattern used by other dashboards.

Key Changes

Removed:

• All old scene-based implementations (summaryScene.ts, errorRateMap.ts, latencyTimeseries.ts, etc.)

[github-actions]

Script size changes

Name	+/-	Main	This PR	Outcome
[263.js]	=	1,715.58 kB	1,715.54 kB	✅
[251.js]	New file	-	799.67 kB	✅
[datasource/module.js]	=	25.00 kB	25.00 kB	✅
[692.js]	=	20.56 kB	20.56 kB	✅
[663.js]	=	5.82 kB	5.82 kB	✅
[module.js]	=	4.90 kB	4.90 kB	✅
[234.js]	Deleted file	805.52 kB	-

Totals

Name	+/-	Main	This PR	Outcome
[Scripts]	-0.23%	2,577.39 kB	2,571.49 kB	✅
[Non-script Assets]	=	2,675.38 kB	2,675.38 kB	✅
[All]	-0.11%	5,252.76 kB	5,246.87 kB	✅

Generated by 🚫 dangerJS against 1adf9b7

[ckbedwell]

It adds the check IDs to the summary table but I quite like that! Great job 👏

[VikaCep]

Yeah! forgot to update the screenshot. Turns out the old method for hiding the column didn't work anymore if we still wanted to use that value to form the link to the check. Glad you like it!