Move deploy/cleanup to cfn/, create 000-prereqs-bucket and 000-prereqs-vpc

Prereq stacks are now tutorials that appear in the list:
  000-prereqs-bucket: shared S3 bucket (setup + cleanup scripts)
  000-prereqs-vpc: shared VPC with public/private subnets

deploy.sh and cleanup.sh moved to cfn/ directory.
All README and CFN interact script references updated.

Author: mwunderl

cleanup.sh cfn/cleanup.shcleanup.sh renamed to cfn/cleanup.sh

@@ -0,0 +1,25 @@
+# Shared tutorial S3 bucket
+
+Creates a shared S3 bucket used by tutorials that need object storage. Tutorials check for this stack automatically — if it exists, they use the shared bucket instead of creating their own.
+
+## Deploy
+
+```bash
+bash tuts/000-prereqs-bucket/prereqs-bucket.sh
+```
+
+## Clean up
+
+```bash
+bash tuts/000-prereqs-bucket/cleanup-prereqs-bucket.sh
+```
+
+## Resources created
+
+- S3 bucket (named `tutorial-bucket-<account>-<region>`)
+- CloudFormation stack `tutorial-prereqs-bucket` (exports the bucket name)
+
+## Used by
+
+Tutorials that create S3 buckets check for this stack first:
+003, 005, 028, 037, 053, 061, 074

deploy.sh cfn/deploy.shdeploy.sh renamed to cfn/deploy.sh

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+# Revision History: 000-prereqs-bucket
+
+## Shell (setup/cleanup scripts)
+
+### 2026-04-20 v1 published
+- Type: functional
+- Initial version: CLI bucket creation + thin CFN stack for exports

tuts/000-prereqs-bucket/README.md

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+# Shared tutorial VPC
+
+Creates a shared VPC with public and private subnets used by tutorials that need networking infrastructure. Tutorials check for this stack automatically.
+
+## Deploy
+
+```bash
+bash tuts/000-prereqs-vpc/prereqs-vpc.sh
+```
+
+## Clean up
+
+```bash
+bash tuts/000-prereqs-vpc/cleanup-prereqs-vpc.sh
+```
+
+## Resources created
+
+- VPC with public and private subnets
+- Internet gateway, NAT gateway
+- Route tables, security groups
+- CloudFormation stack `tutorial-prereqs-vpc-public`
+
+## Used by
+
+Tutorials that create VPCs or need networking:
+002, 008, 012, 015, 047, 055, 064, 075

tuts/000-prereqs-bucket/REVISION-HISTORY.md

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+# Revision History: 000-prereqs-vpc
+
+## CloudFormation
+
+### 2026-04-20 v1 published
+- Type: functional
+- Public VPC with NAT gateway for tutorials needing networking