[IMP] web_timeline: export timeline as SVG

[cyrilfassiau]

[IMP] web_timeline: export timeline as SVG

This PR adds an Export SVG feature to web_timeline, so users can save the currently displayed timeline as an SVG for documentation/reporting purposes (as requested in the related issue discussion).

What’s inside

• Add an Export SVG button in the timeline renderer toolbar.
• Small toolbar layout tweak: wrap the existing buttons in an extra <div> and use flex layout so the new export button is visually separated and easier to find.
• Export implementation:
  • Capture the rendered timeline DOM (vis-timeline)
  • Embed it into an SVG using a foreignObject
  • Inline computed styles to keep the exported SVG visually consistent outside Odoo

Notes / limitations

• The exported SVG relies on foreignObject (compatibility may vary depending on the SVG viewer/editor).
• Tested on a local Odoo instance in modern browsers.

Feedback request

Does this approach match the expected feature described in the issue?
I’m happy to adjust the implementation if another export strategy is preferred.

[OCA-git-bot]

Hi @tarteo,
some modules you are maintaining are being modified, check this out!