Add bandwidth statistics tab with live chart

- Add new Statistics tab between Downloads and Settings
- Implement real-time bandwidth chart using Canvas (60s history)
- Add session overview with 8 stats cards (speed, downloaded, files, packages, etc.)
- Add provider statistics with progress bars
- Add getSessionStats IPC endpoint
- Support dark/light theme in chart rendering

src/shared/ipc.ts

@@ -25,5 +25,6 @@ export const IPC_CHANNELS = {
   PICK_CONTAINERS: "dialog:pick-containers",
   STATE_UPDATE: "state:update",
   CLIPBOARD_DETECTED: "clipboard:detected",
-  TOGGLE_CLIPBOARD: "clipboard:toggle"
+  TOGGLE_CLIPBOARD: "clipboard:toggle",
+  GET_SESSION_STATS: "stats:get-session-stats"
 } as const;

src/shared/preload-api.ts

@@ -2,6 +2,7 @@ import type {
   AddLinksPayload,
   AppSettings,
   DuplicatePolicy,
+  SessionStats,
   StartConflictEntry,
   StartConflictResolutionResult,
   UiSnapshot,
@@ -35,6 +36,7 @@ export interface ElectronApi {
   toggleClipboard: () => Promise<boolean>;
   pickFolder: () => Promise<string | null>;
   pickContainers: () => Promise<string[]>;
+  getSessionStats: () => Promise<SessionStats>;
   onStateUpdate: (callback: (snapshot: UiSnapshot) => void) => () => void;
   onClipboardDetected: (callback: (links: string[]) => void) => () => void;
   onUpdateInstallProgress: (callback: (progress: UpdateInstallProgress) => void) => () => void;

src/shared/types.ts

@@ -226,3 +226,26 @@ export interface ParsedHashEntry {
   algorithm: "crc32" | "md5" | "sha1";
   digest: string;
 }
+
+export interface BandwidthSample {
+  timestamp: number;
+  speedBps: number;
+}
+
+export interface BandwidthStats {
+  samples: BandwidthSample[];
+  currentSpeedBps: number;
+  averageSpeedBps: number;
+  maxSpeedBps: number;
+  totalBytesSession: number;
+  sessionDurationSeconds: number;
+}
+
+export interface SessionStats {
+  bandwidth: BandwidthStats;
+  totalDownloads: number;
+  completedDownloads: number;
+  failedDownloads: number;
+  activeDownloads: number;
+  queuedDownloads: number;
+}