feat(cli): Agent Mode bootstrap + claim flow (Python)

New behavior on `mem0 init`:
  - With no `--email`/`--api-key` AND a positive agent signal (`--agent`,
    global `--json`/`--agent`, or one of the recognized agent env vars
    CLAUDECODE / CURSOR_AGENT / CODEX_CLI / CLINE / CONTINUE / AIDER /
    GOOSE / WINDSURF), bootstrap an unattended Agent Mode account via
    POST /api/v1/auth/agent_mode/. No email, no OTP, no dashboard.
  - With `--email <addr>` AND an existing config that has agent_mode=true,
    run the claim device-flow against the existing key instead of minting
    a fresh one. The raw API key never leaves the device; backend confirms
    claim via the existing CLILoginRequest poll path. Config flips
    agent_mode=false and stamps claimed_at on success.
  - Bare `mem0 init` with no signal + no TTY still errors out — auto-bootstrap
    requires a positive agent signal to avoid surprising pipe-using humans.

New flags:
  --agent   Force unattended Agent Mode bootstrap.
  --source  Channel attribution string for signup_source PostHog property.

Config schema extensions on PlatformConfig:
  agent_mode, created_via, claimed_at, default_user_id.

Telemetry (M1-M6 from the growth doc):
  - cli.init: mode (agent|email|api_key|existing_key), agent_caller,
    signup_source, claimed_agent_mode (bool when --email claims an
    existing agent-mode config).
  - All cli.* events: agent_mode reflects config.platform.agent_mode (the
    bootstrap flag), not the output-format flag — per the growth-doc spec.

cli/python/src/mem0_cli/app.py

@@ -236,7 +236,8 @@ def main_callback(
         _fire_telemetry("version")
         cmd_version()
         raise typer.Exit()
-    if ctx.invoked_subcommand:
+    if ctx.invoked_subcommand and ctx.invoked_subcommand != "init":
+        # init fires its own telemetry from init_cmd.run_init with full M1-M6 props.
         _fire_telemetry(ctx.invoked_subcommand)
 
 
@@ -851,6 +852,12 @@ def init(
     force: bool = typer.Option(
         False, "--force", help="Overwrite existing config without confirmation."
     ),
+    agent_signal: bool = typer.Option(
+        False, "--agent", help="Bootstrap an unattended Agent Mode account (no email required)."
+    ),
+    source: str | None = typer.Option(
+        None, "--source", help="Channel attribution for signup (e.g. github, hn, ph).",
+    ),
 ) -> None:
     """Interactive setup wizard for mem0 CLI.
 
@@ -859,10 +866,20 @@ def init(
       mem0 init --api-key m0-xxx --user-id alice
       mem0 init --email alice@company.com
       mem0 init --email alice@company.com --code 482901
+      mem0 init --agent           # Bootstrap an Agent Mode account (unattended)
+      mem0 init --email alice@company.com  # Claims an existing Agent Mode key when one is present
     """
     from mem0_cli.commands.init_cmd import run_init
 
-    run_init(api_key=api_key, user_id=user_id, email=email, code=code, force=force)
+    run_init(
+        api_key=api_key,
+        user_id=user_id,
+        email=email,
+        code=code,
+        force=force,
+        source=source,
+        agent=agent_signal,
+    )
 
 
 # (entity_app registered at module level, below sub-group definitions)