CLI: streamline startup paths and env parsing

Add shared parseBooleanValue()/isTruthyEnvValue() and apply across CLI, gateway, memory, and live-test flags for consistent env handling.
Introduce route-first fast paths, lazy subcommand registration, and deferred plugin loading to reduce CLI startup overhead.
Centralize config validation via ensureConfigReady() and add config caching/deferred shell env fallback for fewer IO passes.
Harden logger initialization/imports and add focused tests for argv, boolean parsing, frontmatter, and CLI subcommands.

src/utils/boolean.ts

@@ -0,0 +1,24 @@
+export type BooleanParseOptions = {
+  truthy?: string[];
+  falsy?: string[];
+};
+
+const DEFAULT_TRUTHY = ["true", "1", "yes", "on"] as const;
+const DEFAULT_FALSY = ["false", "0", "no", "off"] as const;
+
+export function parseBooleanValue(
+  value: unknown,
+  options: BooleanParseOptions = {},
+): boolean | undefined {
+  if (typeof value === "boolean") return value;
+  if (typeof value !== "string") return undefined;
+  const normalized = value.trim().toLowerCase();
+  if (!normalized) return undefined;
+  const truthy = options.truthy ?? DEFAULT_TRUTHY;
+  const falsy = options.falsy ?? DEFAULT_FALSY;
+  const truthySet = new Set<string>(truthy);
+  const falsySet = new Set<string>(falsy);
+  if (truthySet.has(normalized)) return true;
+  if (falsySet.has(normalized)) return false;
+  return undefined;
+}