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/transcriber.rs

@@ -9,8 +9,8 @@
 //! `whisper` feature — `WhisperRsBackend` (direct whisper-rs, the only
 //! path that pipes `initial_prompt`).
 
-use kon_core::error::Result;
-use kon_core::types::{Segment, TranscriptionOptions};
+use magnotia_core::error::Result;
+use magnotia_core::types::{Segment, TranscriptionOptions};
 
 /// Static capabilities a `Transcriber` advertises to callers.
 ///