Sign panel sessions and isolate test runs

- Replace in-memory auth sessions with signed cookies and signed OAuth state
- Add auth route coverage and update panel/web server wiring
- Switch test script to per-file Bun processes and clean up type checks

shared/lib/logger.ts

@@ -16,7 +16,7 @@ const LogLevelNames = {
     [LogLevel.ERROR]: "ERROR",
 };
 
-export type LogSource = "bot" | "web" | "shared" | "system";
+export type LogSource = "auth" | "bot" | "web" | "shared" | "system";
 
 export interface LogEntry {
     timestamp: string;