feat: render expanded chart at native resolution and add pinch-zoom via MultiGestureCanvas

[abbasifaizan70]

Explanation of Change

Re-renders the expanded chart natively at its target size (via a scaled chart context) instead of raster-upscaling the design-size render, so charts stay sharp on large screens.
Adds pinch/double-tap zoom and pan to the expanded chart using MultiGestureCanvas — the same gestures as the image attachment viewer, as agreed in the follow-up discussion on #95249.
Includes unit tests for the new context-scaling logic.

Fixed Issues

$ #92969
PROPOSAL:#92969 (comment)

Tests

• Verify that no errors appear in the JS console

1. Tap the expand button on the inline chart to open the full-screen modal.
2. Verify the expanded chart is sharp on a large screen (text, axis labels, and lines are crisp, not blurry) and matches the inline chart's layout, only larger.
3. Double-tap (or double-click) the chart and verify it zooms in; double-tap again to zoom back out.
4. Pinch (mobile/trackpad) and verify the chart zooms smoothly within limits.
5. While zoomed in, drag to pan around the chart and verify it stays within bounds.
6. Close the modal and verify the chat is unchanged and no flicker appears.
7. Repeat with a pie chart and verify zoom/pan work and the chart stays clipped/centered like inline.

Offline tests

Same as tests.

QA Steps

• Verify that no errors appear in the JS console

Same as tests.

PR Author Checklist

• I linked the correct issue in the ### Fixed Issues section above
• I wrote clear testing steps that cover the changes made in this PR
  • I added steps for local testing in the Tests section
  • I added steps for the expected offline behavior in the Offline steps section
  • I added steps for Staging and/or Production testing in the QA steps section
  • I added steps to cover failure scenarios (i.e. verify an input displays the correct error message if the entered data is not correct)
  • I turned off my network connection and tested it while offline to ensure it matches the expected behavior (i.e. verify the default avatar icon is displayed if app is offline)
  • I tested this PR with a High Traffic account against the staging or production API to ensure there are no regressions (e.g. long loading states that impact usability).
• I included screenshots or videos for tests on all platforms
• I ran the tests on all platforms & verified they passed on:
  • Android: Native
  • Android: mWeb Chrome
  • iOS: Native
  • iOS: mWeb Safari
  • MacOS: Chrome / Safari
• I verified there are no console errors (if there's a console error not related to the PR, report it or open an issue for it to be fixed)
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• I followed the guidelines as stated in the Review Guidelines
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• I added unit tests for any new feature or bug fix in this PR to help automatically prevent regressions in this user flow.
• If the main branch was merged into this PR after a review, I tested again and verified the outcome was still expected according to the Test steps.

Screenshots/Videos

Android: Native

Screen.Recording.2026-08-04.at.4.24.35.AM.mov

Android: mWeb Chrome

Screen_Recording_20260804_043426_Chrome.mp4

iOS: Native

Screen.Recording.2026-08-04.at.4.12.26.AM.mov

iOS: mWeb Safari

Screen.Recording.2026-08-04.at.3.57.41.AM.mov

MacOS: Chrome / Safari

Screen.Recording.2026-08-04.at.3.42.13.AM.mp4

[codecov]

Codecov Report

❌ Looks like you've decreased code coverage for some files. Please write tests to increase, or at least maintain, the existing level of code coverage. See our documentation here for how to interpret this table.

Files with missing lines	Coverage Δ
...ctoryChartRenderer/context/VictoryChartContext.tsx	95.45% <100.00%> (+89.89%)	⬆️
...artRenderer/utils/scaleVictoryChartContextValue.ts	96.22% <96.22%> (ø)
...artRenderer/components/VictoryChartExpandModal.tsx	1.75% <0.00%> (-0.42%)	⬇️
... and 12 files with indirect coverage changes