feat(reports): add swap usage series to memory chart DEBUG-127 (#46780)

## Problem

The Memory usage chart in the database report showed RAM used, cache,
free, and total, but did not include swap. Swap activity is a meaningful
signal of memory pressure and was only visible in a hidden standalone
chart.

## Fix

Added `swap_usage` (from the `infra-monitoring` provider) as an
additional series in the `ram-usage` Memory chart. The series uses
`omitFromTotal: true` so it does not inflate the stacked total, and
carries the same tooltip text as the hidden standalone swap chart. The
standalone `swap-usage` chart remains hidden as before.

## How to test

- Open the database report for a project on any compute size.
- Navigate to the Memory usage chart.
- Confirm a "Swap" series appears in the legend and renders data
alongside Used, Cache + Buffers, and Free.
- Hover a data point and confirm the tooltip shows a Swap value with the
memory-pressure description.
- Confirm the Swap value does not contribute to the stacked total.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **New Features**
* Added a "Swap" metric to the RAM usage chart in reports, displaying
swap memory usage information with an updated tooltip.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/studio/data/reports/database-charts.ts

@@ -92,6 +92,14 @@ export const getReportAttributesV2: (
           omitFromTotal: true,
           tooltip: 'Total RAM available on this instance',
         },
+        {
+          attribute: 'ram_usage_swap',
+          provider: 'infra-monitoring',
+          label: 'Swap',
+          omitFromTotal: true,
+          tooltip:
+            'Swap space in use by the operating system. Sustained swap usage indicates memory pressure and may degrade database performance',
+        },
       ],
     },
     {