Add tooltips to event field actions

[VibeSWE]

Event detail field actions currently expose only icons, leaving their behavior unclear on hover. Add native tooltips explaining that the filter buttons include or exclude events with the field value, and that copy copies the field name and value.

Validation: Prettier, TypeScript (tsc --noEmit), and the existing Playwright event field search/JSON/exclusion test passed.

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[comment-clanker]

Reviewed commit ecb9471 with four independent agents: two GPT-6.1-Sol reviews (handler semantics and component compatibility) and two Claude Opus 5.5 reviews (UX/accessibility and change risk).

No actionable introduced issues found. The filter tooltips describe equality/exclusion correctly; copy describes the field name and value. Button forwards title to the native button, and existing accessible names and handlers are unchanged. The parent verified the diff contains only three title attributes in RecordSheet.tsx.

Validation passed locally: Prettier, TypeScript, and the existing Playwright event field search/JSON/exclusion test. The Opus reviewers used direct source reads because their shell temporary directory exceeded its quota; they did not independently run tests. Native hover tooltips follow the current UI convention; keyboard-focus/touch tooltips are a possible future enhancement, not a regression.

CI is still pending. Merge only after checks succeed and no unresolved review issues remain.