[AUTO] Add release notes for 3.8.0

[opensearch-ci-bot]

Add release notes for 3.8.0

Borderline Calls

• Add per-item hover navPopover system to the icon side navigation #12285: Placed in Features — could be Enhancements since it extends the existing side navigation, but it introduces a net-new plugin-extensible popover system with a new API surface (navPopover).
• Change the allowed title length to 64 to comply with the collection t… #12421: Placed in Enhancements — could be Bug Fixes since it fixes a failure for long collection names, but the change is a limit relaxation rather than fixing broken logic.
• [Fix] Allow ppl Vega for AE type datasource #12198: Placed in Enhancements — could be Bug Fixes since it removes an incorrect restriction, but it's enabling new functionality for a data source type.
• Replace @amoo-miki/numeral fork with stock @elastic/numeral + BigInt helper #12208: Placed in Maintenance — could be Refactoring since it restructures code, but the primary motivation is removing a personal-scope npm dependency (supply chain concern).
• chore: migrate joi from v14 to v18, remove hoek vulnerability workaround #11957: Placed in Maintenance — could be Infrastructure since it's a major dependency migration, but the primary driver is CVE remediation.
• fix: plugin lint adoption for ESLint 10 (concurrency warning + shared plugin registration) #12362: Placed in Bug Fixes — could be Infrastructure since it relates to linting tooling, but it fixes a broken CI/lint workflow that was incorrectly failing.
• Revert "feat(chat): auto-open chat window on first visit (#12233)" #12309 (revert of [Chat] auto-open chat window on first visit #12233): Placed in Bug Fixes — the revert fixes layout conflicts. The original feature ([Chat] auto-open chat window on first visit #12233) is also listed in Features since both commits exist in the data.
• Hide all sample data for unsupport data source #12288: Placed in Enhancements — could be Bug Fixes since showing sample data for unsupported sources could be considered a bug, but it's more of a UX improvement.
• Enable variable feature in start:explore command #12313: Placed in Enhancements — borderline with Infrastructure since it modifies a dev command, but it enables a feature for developers using that command.
• expose overwriteSavedObjectsWithWorkspaceId so plugin can use it #12204: Placed in Enhancements — could be Bug Fixes since it fixes plugin sample installation in workspaces, but the change exposes a new API surface.
• Refactor TSVB to use client-side math processing #12160: Placed in Refactoring — could be Maintenance since it removes dead code, but the primary change is restructuring the processing pipeline.

[github-actions]

PR Reviewer Guide 🔍

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🧪 No relevant tests

🔒 No security concerns identified

✅ No TODO sections

🔀 No multiple PR themes

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[github-actions]

🔗 Workflow run · commit 9e2925bb693b09d5eeb9b844538827a40ab7e970