🤖 ci: add awscli2 to Nix development shell (#30)

## Summary
Add the AWS CLI (`awscli2`) to the Nix flake development shell so
contributors can run AWS commands without separate local setup.

## Background
Some development and debugging workflows require interacting with AWS
resources. Including the CLI in the shared dev shell keeps tooling
consistent across environments.

## Implementation
- Updated `flake.nix`.
- Added a `# Cloud tooling` section in
`devShells.<system>.default.packages`.
- Included `awscli2` in the package list.

## Validation
- `make verify-vendor`
- `make test`
- `make build`
- `make lint`

## Risks
Low risk. This only adds a development-shell dependency and does not
change runtime/controller behavior.

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Author: ThomasK33

flake.nix

@@ -33,6 +33,9 @@
               kind
               k9s
 
+              # Cloud tooling
+              awscli2
+
               goreleaser
               actionlint
               zizmor