fix: keep Show3D histograms live and publish docs

[bobleesj]

Summary

• Keep independent Show3D panel histograms synchronized with resident playback frames and repaint contrast edits without stopping playback.
• Unblock the GitHub Pages build so the merged Show4DSTEM GIF and Serin Lee acknowledgment reach the hosted documentation.
• Replace the repeated scikit-package paper citation in the PR template with one concise project-workflow link.

Verification

• npm run build
• npm run typecheck
• npm test: 132 passed
• PYTHONPATH=src pytest -q tests/show3d in live-env: 87 passed, 1 skipped
• Full suite: 1114 passed, 16 skipped; 2 unrelated environment-version failures in ShowPtycho provenance and MPS tests
• Jupyter Book built all 59 pages; ShowDiffraction source remained published but was excluded from execution; navigation check passed all 62 generated pages
• Built intro contains the Show4DSTEM GIF and acknowledgment, with matching _images and _static GIF assets
• Phil Chrome on Apple WebGPU: synthetic three-panel and real Caitlyn two-panel stacks stayed resident; histogram curves changed during playback; a same-frame contrast edit repainted in 15 ms while playback remained active

Core checklist

• Focused frontend and browser regression coverage added
• Worktree status and staged diff inspected; no generated reports, screenshots, private data, or notebook state committed
• No notebooks changed

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This PR follows the scikit-package workflow for reproducible scientific software.