docs: update wasmCloud version to 2.9.0

[ericgregory]

Automated version bump from the wasmCloud release pipeline.

Updates src/wasmcloud-version.ts to 2.9.0.
The remark plugin propagates the new value to all {{WASMCLOUD_VERSION}} placeholders
in code blocks across the docs at build time — no other files need editing.

Merging this PR with the release-bump label will auto-cut docs-v2.9.0
(via .github/workflows/tag-after-merge.yml), which fires release-docs.yml and
publishes the offline docs image + tarball.

[netlify]

✅ Deploy Preview for dreamy-golick-5f201e ready!

Name	Link
🔨 Latest commit	45b1e98
🔍 Latest deploy log	https://app.netlify.com/projects/dreamy-golick-5f201e/deploys/6aa18838ca2cdc00085019fe
😎 Deploy Preview	https://deploy-preview-1263--dreamy-golick-5f201e.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[github-actions]

🔎 Structured data validation

• Mode: PR-incremental (base: origin/main)
• Files checked: 26
• JSON-LD payloads: 158
• Errors: 0
• Warnings: 0

✅ All checks pass and no authoring warnings to backfill.

_{⚙️ Generated by ci_structured_data.yml • structured-data spike}