docs: add v1.9.0 server release notes and product update entry

[blue4209211]

Summary

• Adds v1.9.0 server release notes under doc-server/docs/releases/server/1.9.0.md.
• Updates Recent Releases list on doc-server/docs/releases/server/index.md.
• Adds product update announcement entry for 1.9.0 in product-updates/product_updates.json.

Verification

• npm run build in doc-server/ compiled cleanly with zero broken links or markdown errors.
• product-updates/product_updates.json syntax validated.

[gemini-code-assist]

Code Review

This pull request introduces the release notes and documentation updates for NudgeBee version 1.9.0, including the release notes markdown file, an updated server release index, and a new product update announcement. Feedback on the release notes suggests clarifying that bare model IDs are valid for on-demand inference within the same region for AWS Bedrock integrations, while noting that inference profiles are recommended for cross-region routing and availability.

[gemini-code-assist]

When documenting AWS Bedrock integrations, please clarify that bare model IDs are valid for on-demand inference within the same region. Note that while inference profiles are recommended for benefits like cross-region routing and availability, they are not mandatory for on-demand use.

Suggested change

	- feat: Add native Anthropic adapter with thinking parameter controls on AWS Bedrock and Direct API connections
	- feat: Add native Anthropic adapter with thinking parameter controls on AWS Bedrock (where bare model IDs are valid for on-demand inference within the same region, though inference profiles are recommended for cross-region routing and availability) and Direct API connections

References

1. For AWS Bedrock, clarify that bare model IDs are valid for on-demand inference within the same region. Inference profiles are recommended for benefits like cross-region routing and availability, but are not always mandatory for on-demand use.