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.

crates/core/src/hardware.rs

@@ -19,7 +19,7 @@ pub struct CpuInfo {
 }
 
 /// Runtime-detected CPU feature flags relevant to the speech-to-text
-/// and LLM backends Kon ships. All whisper.cpp / llama.cpp / ggml
+/// and LLM backends Magnotia ships. All whisper.cpp / llama.cpp / ggml
 /// kernels degrade roughly two tiers without AVX2, which is why we
 /// surface it separately: when AVX2 is absent, the UI should warn the
 /// user that performance will be a fraction of what they would see