Fix init example

[danielmillerp]

Summary

Remove misleading CLI example from agentex init help text. The example suggested using --template and positional arguments
(agentex init --template temporal my-agent), but the init command only works interactively through prompts.

Bug Description

The help text for agentex init displayed an example that didn't work:

• Shown example: agentex init --template temporal my-agent
• Actual behavior: Command only accepts interactive prompts, no CLI arguments
• Result: Users who tried the example got a "No such option: --template" error

Changes

• Removed the misleading epilog example from main.py:28
• Updated help text to clarify the command is interactive: "Initialize a new agent project with a template (interactive)"

Test Plan

Run agentex init --help and verify:

• No confusing --template example is shown
• Help text clearly indicates the command is interactive