chore: rebrand from Kon/Corbie to Magnotia

Replace all instances of the legacy product names "Kon" and "Corbie" with
"Magnotia" across user-facing copy, code identifiers, package names, bundle
ids, file paths, and documentation. Preserves the unrelated "konsole" (KDE
terminal) reference and the parent CORBEL company name.

- Renames 10 Rust crates (kon-* → magnotia-*) and the tauri binary
- Updates package.json, tauri.conf.json (productName + identifier)
- Renames CSS classes (kon-rh-* → magnotia-rh-*) and animations
- Renames brand and roadmap docs
- Regenerates Cargo.lock and package-lock.json

Verified: svelte-check passes; pure-rust crates compile under new names.

src/lib/i18n/locales/es.json

@@ -2,7 +2,7 @@
   "settings": {
     "title": "Ajustes",
     "language": "Idioma",
-    "languageDescription": "Idioma de la interfaz de Kon. No afecta a la transcripción."
+    "languageDescription": "Idioma de la interfaz de Magnotia. No afecta a la transcripción."
   },
   "history": {
     "title": "Historial",