feat(cli): rework claim to OTP-only — drop device flow + browser + polling

Replace claim_via_device_flow / claimViaDeviceFlow with claim_via_otp /
claimViaOtp. The new flow:
  1. POST /api/v1/auth/email_code/ with the user's email
  2. Prompt for the verification code (or accept via --code for non-TTY)
  3. POST /.../verify/ with {email, code, agent_mode_api_key: <local key>}
  4. Backend's verify_email_code runs upgrade-in-place inline and returns
     {claimed: true, claimed_at, ...}

No browser open, no localhost:3000 frontend dependency, no 10-minute poll
loop. Just two HTTP calls + an OTP prompt. Same upgrade-in-place
semantics on the backend; same key-value-unchanged guarantee for the
caller.

--code flag still supported on `mem0 init --email` for non-interactive
use (CI, agent-driven claim scripts).

cli/node/src/commands/init.ts

@@ -254,7 +254,7 @@ export async function runInit(
 	} = {},
 ): Promise<void> {
 	const { detectAgentCaller } = await import("../agent-detect.js");
-	const { bootstrapViaBackend, claimViaDeviceFlow } = await import("./agent-mode.js");
+	const { bootstrapViaBackend, claimViaOtp } = await import("./agent-mode.js");
 	const { isAgentMode } = await import("../state.js");
 	const { captureEvent } = await import("../telemetry.js");
 
@@ -290,7 +290,7 @@ export async function runInit(
 		const email = opts.email.trim().toLowerCase();
 		validateEmail(email);
 		printInfo(`Claiming Agent Mode account to ${email}...`);
-		await claimViaDeviceFlow(savedConfig, { email });
+		await claimViaOtp(savedConfig, { email, code: opts.code });
 		fireInit("email", true);
 		return;
 	}