fix(fastlane): use store-safe markup in app descriptions

[farfromrefug]

Summary

Store descriptions are shared between renderers that do not support the same markup, so the files
now stick to the subset that works everywhere.

• Android (full_description.txt, both apps): section headers use <b>, bullets use •, sections
  are separated by blank lines. No <ul>/<li> (Google Play does not render them) and no <p>
  (unsupported on both Play and F-Droid). This also removes the <p> markup that fr-FR and de-DE
  were shipping to Play.
• iOS (description.txt): now mirrors the android en-US content, in plain text — App Store
  Connect renders no markup at all. The com.akylas.cardwallet iOS description did not exist and was
  added.
• Wording is unchanged everywhere; only markup and bullet characters were touched.

Why the subset: F-Droid supports b/i/u/br/ul/ol/li/… and converts every newline to <br>, while
Google Play only supports b/i/u/br plus entities. The intersection is <b>, <i>, <u>, <br>,
literal bullet characters and blank-line paragraphs.

Testing

Metadata only — no app code touched, so no unit tests or svelte-check apply. Checked:

• every description under the 4000-char store limit (largest is 2061)
• no <p>/<ul>/<li>/<h*> left in any full_description.txt
• no markup at all in either iOS description.txt
• normalized diff confirms no wording changed

Actual store rendering can only be confirmed at the next release (upload_store / deliver with
upload_metadata, and the next F-Droid/IzzyOnDroid build).

Refs #682