chore(release): prepare v0.5.0-beta (#148)

This commit prepares the repository for the v0.5.0-beta release,
transitioning from alpha to beta status.

Changes made:
- Update version from 0.4.1-alpha to 0.5.0-beta in version.py
- Update Development Status classifier from Alpha to Beta in pyproject.toml and setup.py
- Update status badges from Alpha (orange) to Beta (blue) in README.md
- Update all installation command examples to use v0.5.0-beta tag
- Update release announcement from Alpha to Beta in README.md
- Add RELEASE_PROCESS.md documentation for future releases
- Update docs/INSTALL.md with new version references
- Add What's New section for v0.5.0-beta in docs/UPDATE.md
- Update SECURITY.md supported versions table
- Update website schema softwareVersion in layout.tsx
- Update website version badges in page.tsx
- Update website package.json version to 0.5.0

Testing:
- All 463 tests passing (100%)
- Version consistency verified across all files

Release process documentation added to docs/RELEASE_PROCESS.md

web/src/app/layout.tsx

@@ -120,7 +120,7 @@ export default function RootLayout({
       "priceCurrency": "USD"
     },
     "description": "Free, open-source voice dictation for Linux. 100% offline with Whisper AI and VOSK. Works with X11 and Wayland.",
-    "softwareVersion": "0.4.1-alpha",
+    "softwareVersion": "0.5.0-beta",
     "author": {
       "@type": "Person",
       "name": "Jatin K Malik",

web/src/app/page.tsx

@@ -204,7 +204,7 @@ export default function HomePage() {
             />
             <span className="font-bold text-lg sm:text-xl">Vocalinux</span>
             <span className="hidden sm:inline-block text-xs bg-gradient-to-r from-primary/20 to-green-500/20 text-primary border border-primary/30 px-2.5 py-1 rounded-full font-semibold shadow-sm shadow-primary/20">
-              v0.4.1 Alpha
+              v0.5.0 Beta
             </span>
           </Link>
 
@@ -307,7 +307,7 @@ export default function HomePage() {
               <div className="inline-flex items-center gap-2 bg-primary/10 px-4 py-2 rounded-full mb-6">
                 <Sparkles className="h-4 w-4 text-primary" />
                 <span className="text-sm font-medium text-primary">
-                  Alpha Release — Try it now!
+                  Beta Release — Try it now!
                 </span>
               </div>