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/cloud-providers/Cargo.toml

@@ -1,8 +1,8 @@
 [package]
-name = "kon-cloud-providers"
+name = "magnotia-cloud-providers"
 version = "0.1.0"
 edition = "2021"
-description = "BYOK cloud STT provider stubs and API key storage for Kon"
+description = "BYOK cloud STT provider stubs and API key storage for Magnotia"
 
 [dependencies]
-kon-core = { path = "../core" }
+magnotia-core = { path = "../core" }