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.

docs/brief/user-sentiment.md

@@ -1,4 +1,4 @@
-<!-- Source: Kon Master Brief — §12 Live User Sentiment -->
+<!-- Source: Magnotia Master Brief — §12 Live User Sentiment -->
 
 ## 12. Live User Sentiment — What Neurodivergent Users Actually Say
 
@@ -17,7 +17,7 @@ The dominant emotional narrative across every neurodivergent community: download
 ### Emotional intensity
 Language consistently involves shame ("another thing I'm failing at"), resignation ("I've lost count"), and liberation when users find the right framing ("I wasn't broken — I was working with tools designed for someone else's operating system"). Anger directed specifically at subscription billing: one Effecto review reads "Pretty ironic that it's an app supposed to be ADHD-friendly yet charges you for a service you don't use." A Wisey Trustpilot review states: "They are unscrupulous and taking advantage of people with ADHD who may be less organised."
 
-### Demand signals for Kon's specific features
+### Demand signals for Magnotia's specific features
 - **Voice-first capture** receives consistent praise wherever it appears — one user who deleted 47 apps kept a voice memo tool as one of three survivors.
 - **Offline/local-first** positioning is an emerging differentiator; community responds positively to "your data stays with you."
 - **One-time purchase preference** is acute: a Goblin Tools App Store reviewer wrote "The fact it isn't subscription-based is incredibly helpful — I know it's mine and can use it whenever I need, without having to worry about whether it's 'worth it' each month or if I'm going to forget to cancel."