Test graph PDF output with more than 1000 points

[lorenzozanee]

Adds a deterministic browser integration fixture for 1000 and 1001 point graphs. The test emulates print media and exercises Chrome Page.printToPDF while preserving the existing graph and browser-log assertions.

The assertion verifies a valid non-empty PDF and a visible SVG trace; it does not inspect rendered PDF pixels, so cross-browser validation remains for CI and maintainers.

Contributor Checklist

• I have broken down my PR scope into the following TODO tasks
  • task 1
  • task 2
• I have run the tests locally and they passed. (refer to testing section in contributing)
• I have added tests, or extended existing tests, to cover any new features or bugs fixed in this PR

optionals

• I have added entry in the CHANGELOG.md
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  • this GitHub #PR number updates the dash docs
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Fixes #3889

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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