epic: Better onboarding experience

[imtuyethan]

Objectives

Provide the smoothest / white glove experience that introduces users what Jan is with its main features, guiding them through their initial setup.

Specs

https://www.notion.so/jan-ai/Better-Onboarding-Experience-d7f9d944646c4ce7b412bd65a14d5db1?pvs=4

Key user stories

For new users:

• 1st Screen: Let users customize their Jan data folder.
• 2nd Screen: Collect email
• Starter screen: Guide users on how to choose model

For current user base:

• Only 1 screen: Collect email (it only shows up once, & show up the next time users open Jan app).

Design

Figma: https://www.figma.com/design/DYfpMhf8qiSReKvYooBgDV/Jan-App-(3rd-version)?node-id=3676-88891

[dan-homebrew]

We should re-evaluate this after Jan and Cortex refactor:

• Data folder is now mostly replaced by OS Application default for Jan
  • Threads are now handled by SQlite DB
• Privacy permissions are are opt-in, and not during onboarding

[imtuyethan]

Added another example on why allowing users to customize Jan Data Folder upon installation is important: https://discord.com/channels/1107178041848909847/1299405423866282046

In university and restricted environments, apps are blocked from executing from User/Apps folder. Currently, Jan doesn't allow users to choose installation location, forcing manual folder moves post-installation which is inconvenient and may cause permission issues.