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/pricing-model.md

@@ -1,11 +1,11 @@
-<!-- Source: Kon Master Brief — §5 Pricing Model -->
+<!-- Source: Magnotia Master Brief — §5 Pricing Model -->
 
 ## 5. Pricing Model
 
 ### Free tier
 Basic voice capture + local transcription + simple task list. Limited functionality (e.g. 5 active tasks or 10 stored transcriptions). Top-of-funnel — proves the core value loop.
 
-### Kon Pro — lifetime licence
+### Magnotia Pro — lifetime licence
 | Platform | Price |
 |---|---|
 | Desktop (Windows/macOS/Linux) | £49 |
@@ -16,7 +16,7 @@ Full feature set, all running locally. Unlimited transcription, templates, profi
 
 **Positioning:** "They took away lifetime. We never will."
 
-### Kon Cloud — optional subscription (£4.99/month or £39.99/year)
+### Magnotia Cloud — optional subscription (£4.99/month or £39.99/year)
 Access to frontier AI model (Claude, GPT-4o, or similar) for:
 - Higher-accuracy transcription of specialist vocabulary
 - Smarter task decomposition
@@ -44,7 +44,7 @@ This is the only recurring revenue stream and is genuinely tied to per-request A
 
 ### Pre-launch pricing validation (Van Westendorp)
 Before committing to £49, send the waitlist a four-question survey via Tally (free):
-1. At what price would Kon be so expensive you'd never buy it?
+1. At what price would Magnotia be so expensive you'd never buy it?
 2. At what price would it seem so cheap you'd doubt its quality?
 3. At what price is it getting expensive but you'd still consider it?
 4. At what price is it a bargain?