Tighten browser summary report layout for RMarkdown parity

[uriahf]

Summary of changes

1. Baseline SHA / Version:

   • Starting main SHA: d4b71aa89326491ffc7363bf9daa61bb39d36341
   • Package version: 0.0.7
   • Vendored rtichoke_viz version: 0.15.0 (unmodified)

2. Exact CSS/Layout Differences Changed:

   • Scoped .rtichoke-report max-width to 1040px (previously 1200px).
   • Scoped embedded chart heights: .rtichoke-report .rtichoke-viz-chart set to 500px min-height/height (previously 600px), .rtichoke-report .rtichoke-calibration set to 550px min-height/height.
   • Tightened report vertical gaps scale:
     • Report (.rtichoke-report): 1.5rem
     • Section (.rtichoke-report__section): 1.25rem
     • Group (.rtichoke-report__group): 0.875rem
     • Component & Tabpanel (.rtichoke-report__component, .rtichoke-report__tabpanel): 0.5rem

3. Resulting Report Width: 1040px

4. Resulting Embedded Chart Heights: 500px (ROC, Lift, PR, Gains, Decision Curve, IA), 550px (Calibration)

5. Resulting Spacing Values: 1.5rem / 1.25rem / 0.875rem / 0.5rem

6. Confirmation Standalone Charts Are Unaffected: Verified that standalone .rtichoke-viz-chart widgets outside summary reports preserve default sizing.

7. Tests Added/Updated:

   • tests/testthat/test-report-browser.R: Updated HTML tag assertions for density CSS rules.
   • tests/testthat/test-summary-report-browser.R: Updated headless browser test assertions for max-width and chart heights.

8. Validation Results: All tests and SHA256 integrity verifications passed.

9. Files Changed:

   • R/report_browser.R
   • tests/testthat/test-report-browser.R
   • tests/testthat/test-summary-report-browser.R

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PR created automatically by Jules for task 13317718407801580901 started by @uriahf

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