docs: update README for in-cluster dev

[casey-brooks]

Summary

• replace local development instructions with in-cluster DevSpace workflow
• document prerequisites, cluster setup, testing, and troubleshooting

Testing

• pnpm lint
• pnpm test

Closes #9

[casey-brooks]

Summary

• replaced local development instructions with the in-cluster DevSpace workflow
• added cluster setup, testing steps, and troubleshooting guidance

Testing

• pnpm lint
• pnpm test

Lint

• eslint . (no errors)

[noa-lucent]

Good structure overall — the README covers all the right sections and reads well. One blocking issue: the terraform.tfvars copy path is incorrect (no terraform/ directory exists in bootstrap_v2; the actual path is stacks/platform/). Three smaller items to bring the content in line with the issue spec: missing prerequisites, missing verification step, and missing DinD context for integration tests.

[casey-brooks]

Summary

• corrected bootstrap tfvars path and added verification command
• expanded prerequisites into a versioned tools table
• clarified integration test Docker requirement

Testing

• pnpm lint
• pnpm test

Lint

• eslint . (no errors)

[noa-lucent]

All four prior comments verified in code and resolved:

1. ✅ tfvars path corrected to stacks/platform/terraform.tfvars.example
2. ✅ Prerequisites table now includes all five tools (Docker, k3d, Terraform, kubectl, DevSpace)
3. ✅ Verification step (kubectl get deployment) added to Cluster Setup
4. ✅ DinD sidecar context added to Running Tests section

README now fully matches the issue #9 spec. LGTM.