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/assets/wordmark.svg

@@ -1,5 +1,5 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 240 80" width="240" height="80">
-  <text x="12" y="54" font-family="&#39;Instrument Serif&#39;, Georgia, serif" font-style="italic" font-weight="400" font-size="48" fill="#e8a87c" letter-spacing="-0.01em">Kon</text>
+  <text x="12" y="54" font-family="&#39;Instrument Serif&#39;, Georgia, serif" font-style="italic" font-weight="400" font-size="48" fill="#e8a87c" letter-spacing="-0.01em">Magnotia</text>
   <text x="92" y="46" font-family="&#39;Instrument Serif&#39;, Georgia, serif" font-size="28" fill="#e8a87c">ක</text>
   <text x="12" y="70" font-family="&#39;Lexend&#39;, sans-serif" font-size="9" fill="#716b60" letter-spacing="1.4" text-transform="uppercase" style="text-transform:uppercase">THINK OUT LOUD</text>
 </svg>