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/transcription/src/concurrency.rs

@@ -1,7 +1,7 @@
 use std::sync::Arc;
 
-use kon_core::error::{KonError, Result};
-use kon_core::types::{AudioSamples, TranscriptionOptions};
+use magnotia_core::error::{MagnotiaError, Result};
+use magnotia_core::types::{AudioSamples, TranscriptionOptions};
 
 use crate::local_engine::{LocalEngine, TimedTranscript};
 
@@ -14,5 +14,5 @@ pub async fn run_inference(
 ) -> Result<TimedTranscript> {
     tokio::task::spawn_blocking(move || engine.transcribe_sync(&audio, &options))
         .await
-        .map_err(|e| KonError::TranscriptionFailed(format!("Task join error: {e}")))?
+        .map_err(|e| MagnotiaError::TranscriptionFailed(format!("Task join error: {e}")))?
 }