Auto-run, pre-rendering, and PanelLive server component

[MarcSkovMadsen]

PR: Auto-run, pre-rendering, and PanelLive server component

Summary

This PR adds three major features: click-to-run with pre-rendering, a PanelLive JSComponent for Panel server apps, and bundled in-package assets for pip installs.

What changed

Auto-run and pre-rendering

• auto-run="false" is now the default in MkDocs fences -- examples require a click to activate Pyodide
• PanelLive.runAll() API for sequential execution of all <panel-live> elements on a page
• Pre-rendering: build-time execution of Panel code produces static Bokeh JSON shown as a preview until Pyodide loads
• panel-live pre-render CLI command for build-time rendering
• preview attribute for static image placeholders (PNG/GIF) with "Run" badge overlay
• Content-hash caching in .panel-live/ to avoid redundant re-renders
• Sphinx directive and Quarto Lua filter support for pre-rendering

PanelLive server component

• PanelLive JSComponent wrapping <panel-live> for use in panel serve apps
• 6 modes: editor, app, playground, headless, progress, debug
• evaluate() -- execute Python in the browser and return the result to the server
• run() -- trigger the full render pipeline programmatically from the server
• input param -- server-to-client reactive data push (no re-run needed)
• output param -- client-to-server data via server.output
• send() -- push arbitrary JSON data to client-side code
• Progress mode: spinning Python icon with CSS tooltip showing queue depth
• Shadow DOM workarounds (getElementById patch, CSS mirroring) for Bokeh compatibility
• ESM module with bidirectional messaging bridge

CLI and packaging

• panel-live serve command serves the showcase app with auto-discovered assets
• Asset discovery: dist/ (repo dev) -> static/ (pip install) -> CDN fallback
• JS/CSS bundled in src/panel_live/static/ -- pip install panel-live works out of the box
• pixi run serve-showcase task chains build-js + serve for always-fresh dev workflow
• pixi run sync-static task copies built assets into the package for wheel builds

Showcase app

• 11-section demo: all 6 modes, server RPC (evaluate/run), reactive push, periodic push, client-to-server data
• Branded logo bar (Panel + Pyodide) with documentation links
• Playwright smoke test (tests/ui/test_showcase.py)

Web component improvements

• Element registry with registerElement()/unregisterElement() for document-order tracking
• <panel-live-config> element for declarative configuration
• Worker stall detection and crash recovery (45s timeout, 1 retry)
• JSPI disabled by default (fixes Chrome 137+ STATUS_ACCESS_VIOLATION crashes)
• Dark/light theme improvements in the editor and tooltip

CI fix

• Added permissions: contents: write to pre_commit job for PNG optimization auto-commit

Files changed

97 files, +11609 / -2386 lines across:

• src/panel_live/ -- Python package (component, CLI, ESM, pre-render, fences, sphinx)
• lib/ -- JS source modules (registry, config-element, theme, worker-bridge, panel-live-element)
• tests/ -- 178 Python tests, 178 JS tests, Playwright smoke test
• docs/ -- updated how-to guides, tutorials, examples, open/closed issues
• docs-sphinx/, docs-quarto/ -- extension test sites updated
• quarto/_extensions/ -- Lua filter and bundled assets updated
• .github/workflows/ci.yml -- permissions fix

Testing

• pixi run test -- 178 passed, 4 skipped
• pixi run test-js -- 178 passed (12 test files)
• pixi run lint -- all checks passed
• Team review (6 agents) found and fixed 3 bugs: tooltip style injection singleton, CLI empty-dir edge case, stale static assets