Rename Wrystr to Vega

Named after Jurij Vega (1754-1802), Slovenian mathematician who made
knowledge accessible through his logarithm tables. Rebrand before
OpenSats application (April 1).

- Product name, window title, identifiers, binary name all renamed
- Cargo package: wrystr -> vega, wrystr_lib -> vega_lib
- PKGBUILD: wrystr -> vega (new AUR package name)
- Release workflow: artifact names, release text updated
- README: new tagline referencing Jurij Vega
- DB migration: auto-renames wrystr.db -> vega.db on first launch
- Keyring service name kept as "wrystr" for backward compatibility
- localStorage keys kept as wrystr_* to preserve existing user data

Pending manual steps:
- Rename GitHub repo hoornet/wrystr -> hoornet/vega
- Create new AUR package vega-git, orphan wrystr-git
- Update local .desktop launcher

src/components/feed/FountainCard.tsx

@@ -89,7 +89,7 @@ export function FountainCard({ seg }: { seg: ContentSegment }) {
         <button
           onClick={handlePlay}
           className="shrink-0 w-8 h-8 rounded-full border border-border flex items-center justify-center hover:bg-accent/10 transition-colors"
-          title="Play in Wrystr"
+          title="Play in Vega"
         >
           <svg width="10" height="12" viewBox="0 0 10 12" fill="currentColor" className="text-accent ml-0.5">
             <polygon points="0,0 10,6 0,12" />

src/components/feed/MediaCards.tsx

@@ -64,7 +64,7 @@ export function AudioBlock({ sources }: { sources: string[] }) {
             </div>
             <div className="min-w-0 flex-1">
               <div className="text-[12px] text-text truncate">{name}</div>
-              <div className="text-[10px] text-text-dim">audio · play in wrystr</div>
+              <div className="text-[10px] text-text-dim">audio · play in vega</div>
             </div>
           </button>
         );