[Docs] Add dedicated stylus support page and link it from FAQ

[YuF-9468]

Summary

Closes #1039.

This adds a dedicated documentation page for stylus support and links to it from the FAQ entries that previously only contained short notes.

What changed

• Added community/stylus-support with:
  • platform support expectations
  • stylus-related settings (Pen-only input, Ignore pressure, Input test)
  • pen shortcut note
  • relevant Flutter tracking issues for Android/Windows/Linux
• Added a sidebar entry under Community for Stylus support.
• Added links from FAQ stylus questions to the new page.

Why this helps

Users now have one clear page to check stylus behavior and known limitations instead of searching multiple FAQ snippets.

Risk

Docs-only change; no runtime behavior modified.

[CodeDoctorDE]

Thanks for contributing.
However I would add more things

• Mention that the pen shortcuts can be configured in settings -> input -> pen
• Mention Pointer Test if something wrong. Primary Button corresponds to 10 (2), Secondary Button which corresponds to 100 (4) or 100000 (32). Also describe the button is a bit mapping
• Mention the new Pen Only Toggle that is activated if stylus has been detected (can be turned off in the pen input settings)

[YuF-9468]

Thanks for the review — updated in the latest commit.

Addressed all requested points:

• Added explicit settings path: Settings -> Input -> Pen
• Added Pointer Test button mapping details (primary 10 (2), secondary 100 (4) / 100000 (32)) and clarified these are bit mappings
• Added note about the Pen-only toggle being activated on stylus detection and that it can be disabled in Pen input settings

Please take another look when you have time.

[Copilot]

Pull request overview

This PR adds a dedicated documentation page for stylus/pen-input support in Butterfly, closing issue #1039. It consolidates information previously scattered across FAQ entries (platform support, settings, pen shortcuts, known Flutter framework limitations) into a single reference page, and adds links from the relevant FAQ questions to this new page.

Changes:

• Added a new stylus-support.md page under community/ covering supported platforms, stylus settings, pen shortcut button values, and known Flutter tracking issues.
• Added links from two FAQ entries (Mobile S-Pen and Desktop stylus) to the new page.
• Added a sidebar entry for "Stylus support" in the Community section of astro.config.mjs.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
docs/src/content/docs/community/stylus-support.md	New dedicated stylus support page with platform support, settings, shortcuts, and known issues
docs/src/content/docs/community/faq.md	Adds "See Stylus support" links before existing FAQ answers on S-Pen and desktop stylus topics
docs/astro.config.mjs	Adds "Stylus support" sidebar entry under the Community section

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[Copilot]

The button values listed — 10, 100, and 100000 — appear to be binary representations of the pointer button bit flags (where 10 in binary = 2 decimal, 100 in binary = 4 decimal, and 100000 in binary = 32 decimal). The page states "These values are bit mappings from pointer button flags," but does not clarify the numeric base being used. Without explicitly noting that these are binary values (or using a 0b prefix notation), readers are likely to interpret 10, 100, and 100000 as decimal numbers, which would be incorrect and confusing. Consider adding a clarifying note that these outer values are written in binary.

Suggested change

	These values are bit mappings from pointer button flags.
	These values are bit mappings from pointer button flags, where the outer values (for example, `10`, `100`, `100000`) are written in binary and the values in parentheses are their decimal equivalents.

[CodeDoctorDE]

I have copilot reviewed the changes. Can you add a stylus_support translation in docs/src/translations/en.josn?

[YuF-9468]

Done ✅ Added stylus_support translation entry to docs/src/translations/en.json (note: filename is en.json).

Commit: 8b61faa

[CodeDoctorDE]

thanks for contributing