Feat: Add organization name to setup flow

[shyamsalimkumar]

What changed

• The owner setup wizard now includes an Organization Name field (defaults to Demo)
• Added frontend tests for the full owner setup wizard flow
• Fixed two test infrastructure issues that blocked the new tests from running

Why

Self-hosted instances were always created with the organization name Demo with no way to change it during setup. Fine for single-command turbo installs, but not acceptable for real self-hosted deployments as mentioned in #1665

How

Organization name field

• Added organization_name to SetupOwnerRequest on the backend; if absent, defaults to "Demo" so existing integrations and the turbo install path are unaffected
• Added the field to the first step of the setup wizard with autoComplete="organization" to prevent browsers autofilling a city name

Test infrastructure fixes

• Added noValidate to the owner step form — without it, jsdom's HTML5 type="email" constraint validation blocks form submit before React's custom validation runs, making the invalid-email test untestable
• Added a ResizeObserver stub to the global test setup — Radix UI's Checkbox component (used in the SMTP config step) calls new ResizeObserver() on mount and crashes in jsdom without it

New tests

• Full wizard flow coverage: owner form validation, private network step, SMTP prompt, SMTP config validation, and API submission (including organization_name payload, error handling, and 409 conflict)

Breaking changes

None. organization_name is optional on the API — omitting it falls back to "Demo".

[superplanehq-integration]

👋 Commands for maintainers:

• /sp start - Start an ephemeral machine (takes ~30s)
• /sp stop - Stop a running machine (auto-executed on pr close)

[shiroyasha]

@shyamsalimkumar thank you for opening this PR! Sorry for not reviewing it on time.

1/ Can you maybe attach a screenshot of the owner page? 🙏
2/ Before we can legally use this PR on our open source project, we would need you to sign the DCO https://github.com/superplanehq/superplane/blob/main/docs/contributing/commit_sign-off.md

[shiroyasha]

I'll close this PR for now, even thought I would really like to have it merged.

@shyamsalimkumar thank you for opening this one. Please re-open the PR when the DCO is signed.

[shyamsalimkumar]

@shiroyasha Attaching the screenshots you'd requested. Rebased, (and force pushed) my changes on top of the latest main branch, and signed the commits.
Unsure how to open a closed PR though.