feat(demo): make demo user staff by default + use system theme

[thmsobrmlr]

Problem

Follow up to #39711

Changes

• makes the demo user staff by default
• uses the system theme for the user

How did you test this code?

Re-created my local environment

[posthog-bot]

Hey @thmsobrmlr! 👋
This pull request seems to contain no description. Please add useful context, rationale, and/or any other information that will help make sense of this change now and in the distant Mars-based future.

[andehen]

💖

[greptile-apps]

_{2 files reviewed, 1 comment}

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[greptile-apps]

syntax: "Wether" is misspelled

Suggested change

	default=True,
	help="Whether the demo user should be a staff user (default: True)",

Prompt To Fix With AI

This is a comment left during a code review.
Path: posthog/management/commands/generate_demo_data.py
Line: 84:84

Comment:
**syntax:** "Wether" is misspelled

```suggestion
            help="Whether the demo user should be a staff user (default: True)",
```

How can I resolve this? If you propose a fix, please make it concise.

[graphite-app]

There's a typo in the help text: Wether should be Whether.

Suggested change

	help="Wether the demo user should be a staff user (default: True)",
	help="Whether the demo user should be a staff user (default: True)",

Spotted by Graphite Agent



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