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/issues/runtime-capabilities-accelerators.md

@@ -29,9 +29,9 @@ Five regression tests in `commands::models::tests` cover:
 - `non_macos_with_loader_advertises_vulkan`
 - `cpu_is_always_first_entry` (contract the frontend relies on)
 
-Both `cargo test -p kon --lib` and `cargo test -p kon --lib
---no-default-features` pass the new suite; both `cargo build -p kon`
-and `cargo build -p kon --no-default-features` compile clean.
+Both `cargo test -p magnotia --lib` and `cargo test -p magnotia --lib
+--no-default-features` pass the new suite; both `cargo build -p magnotia`
+and `cargo build -p magnotia --no-default-features` compile clean.
 
 Runtime GUI verification on a real macOS box is still on the ship-gate
 checklist — the detection logic is correct in code; Metal-loader