feat: Inkless doc updates

[harshini-rangaswamy]

Describe your changes

Documentation updates for the Inkless Cloud internal release, including:

• Updates to the Kafka service creation flow to reflect Inkless and Classic Kafka service types and deployment modes.
• A new Inkless overview describing core concepts, key differences from Classic Kafka, and behavior for existing services.
• Documentation for the AKU-based usage and billing model, covering compute (AKU-hours), storage, and topic ingress and egress.

Autoscaling documentation is not included.

POD-1752

Preview:

• Overview: https://pod-1752-documentation-for-i.aiven-docs.pages.dev/docs/products/kafka/concepts/inkless
• Create service flow: https://pod-1752-documentation-for-i.aiven-docs.pages.dev/docs/products/kafka/create-kafka-service
• AKU plans: https://pod-1752-documentation-for-i.aiven-docs.pages.dev/docs/products/kafka/concepts/inkless-aku
• Billing: https://pod-1752-documentation-for-i.aiven-docs.pages.dev/docs/products/kafka/concepts/inkless-aku

Checklist

• The first paragraph of the page is on one line.
• The other lines have a line break at 90 characters.
• I checked the output.
• I applied the style guide.
• My links start with /docs/.

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Deploying aiven-docs with    Cloudflare Pages

Latest commit:	4ec0058
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Preview URL:	https://7a0923d4.aiven-docs.pages.dev
Branch Preview URL:	https://pod-1752-documentation-for-i.aiven-docs.pages.dev

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[Stuzanna]

Let's confirm, it will have some affect. e.g. if high throughput topic you will be tiering a lot more data, which takes CPU

[Stuzanna]

Suggested change

Local disk used by brokers is not billed.

[Stuzanna]

I need to check, but I think it is included in storage total, rather than not billed

[Stuzanna]

This will likely be split by topic type

[Stuzanna]

@harshini-rangaswamy thanks for the work so far, I have left some comments to do with phrasing on number of AKU , rather than level, and where we will want to add more as the PR develops.

[harshini-rangaswamy]

@harshini-rangaswamy thanks for the work so far, I have left some comments to do with phrasing on number of AKU , rather than level, and where we will want to add more as the PR develops.

Thanks for the review. I have updated the wording to use number of AKUs instead of AKU level. The remaining comments are pending confirmation.