feat(tray): routing switch, live tooltip/icon, ping in recent list

[loss-and-quick]

Summary

Overhauls the system-tray right-click menu, borrowing v2rayN's tray UX where it fits kasumi's TUN-only model (system-proxy set/clear/PAC was intentionally left out — kasumi has no OS-proxy concept).

• Routing-mode radio submenu (Rules / Global / Custom) — a check-marked submenu that writes settings.routingMode without opening the window, mirroring v2rayN's routing submenu. Clicks come back through the existing TrayAction catch-all as routing:<mode>; Tauri has no native radio item, so (like v2rayN) exactly one entry is check-marked.
• Live tooltip + state icon — a new lightweight set_tray_status command pushes a tooltip (Kasumi Proxy — <state> · <profile> + live ↓/↑ rate) and a state icon on every status tick. Icon variants (full colour / desaturated / muted) are derived at runtime from the bundled icon, so no new art is committed. The menu is rebuilt only when its contents change (not per traffic tick), and the icon is swapped only on a state transition.
• Ping in the recent list — recent-profile entries append the last measured latency (· N ms) when a result exists.

Reuses existing settings.routing* i18n keys, formatRate, and testResults — no new locale keys, no duplicated values.

Tooltips are honoured on Windows/macOS; the Linux app-indicator ignores them, but the state icon still updates there.

Affected layer

• frontend/ — React Web UI
• crates/ · src-tauri/ — Rust core / backend / Tauri desktop
• module/ — Android installable zip (thin launcher over the Rust daemon)
• scripts/ — build / release helpers
• CI / .github/
• Docs only

Verification

Rust (crates/ · src-tauri/):

• cargo fmt --all --check
• cargo clippy --workspace --all-targets -- -D warnings
• cargo test --workspace — green except one pre-existing, network-dependent test (net::tcp_ping_fails_on_unreachable_host) that also fails on main in the sandbox; unrelated to this change. cargo test -p kasumi-desktop is fully green (28/28).
• Codegen drift: cargo run -p kasumi-desktop --bin codegen leaves git clean

Web UI (frontend/):

• bun run check — Biome lint + format clean
• bun run test — vitest green (68/68)
• bun run build — tsc -b + vite build succeed
• bun run check:i18n — locale dictionaries in sync

Module shell (module/):

• shellcheck -s sh module/*.sh — n/a, not touched

Checklist

• Title is a scoped Conventional Commit; commits are logically split
• No build artifacts committed
• Generated frontend/src/generated/ was regenerated from Rust, not hand-edited
• If user-visible strings changed: n/a — no new strings, reuses existing settings.routing* keys
• Renames touching the project id were grepped in all case forms — n/a, no renames

Notes for reviewers

• The three sub-features form one cohesive tray overhaul and their diffs interleave (a single useEffect deps line and the regenerated bindings.ts both mix features), so they land as one commit rather than an artificial split into non-compiling intermediates.
• State icons are generated in-process (desaturate + dim the bundled 128x128.png via Image::from_bytes / new_owned) rather than shipping extra PNGs — image-png is already enabled.
• Manual runtime check (right-click → switch routing mode, watch icon change on connect/disconnect) is left to a desktop run; static + unit checks all pass.