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.

run.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# Kon dev launcher. Starts Vite first, waits for it to bind port 1420,
+# Magnotia dev launcher. Starts Vite first, waits for it to bind port 1420,
 # then runs Tauri without triggering a second Vite instance.
 # For performance testing use: npm run tauri build
 set -euo pipefail