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/audio/src/concurrency.rs

@@ -1,7 +1,7 @@
 use std::path::Path;
 
-use kon_core::error::Result;
-use kon_core::types::AudioSamples;
+use magnotia_core::error::Result;
+use magnotia_core::types::AudioSamples;
 
 use crate::decode::decode_audio_file;
 use crate::resample::resample_to_16khz;
@@ -15,5 +15,5 @@ pub async fn decode_and_resample(path: &Path) -> Result<AudioSamples> {
         resample_to_16khz(&audio)
     })
     .await
-    .map_err(|e| kon_core::error::KonError::AudioDecodeFailed(format!("Task join error: {e}")))?
+    .map_err(|e| magnotia_core::error::MagnotiaError::AudioDecodeFailed(format!("Task join error: {e}")))?
 }