## What
- **Extract the AI sparkle into a shared component.** Moves the
Gemini-style gradient sparkle from
`components/transactions/ai-sparkle-icon` →
`components/ui/ai-sparkle-icon`. It's now the single icon to reuse
wherever a feature involves AI. Existing transaction-list usages
(`category-cell`, `transaction-filters`) point at the new path; no
visual change there.
- **Mark AI-generated automation rules.** In the Automation Rules table,
the rule **title** is now prefixed with the sparkle (tooltip +
`aria-label "Created by AI"`) when the rule's `origin` is `ai`.
Extracted into a small `AutomationRuleTitle` component.
The backend `origin` enum (`RuleOrigin`: user/ai) already shipped to
`main`; this PR is the frontend surface plus the `origin` field on the
TS `AutomationRule` type.
## Tests
- New `automation-rule-title.test.tsx`: sparkle shown for `origin:
'ai'`, absent for `'user'`.
- `bun run format`, `bun run lint` clean; vitest green.
## Note
Per review, the marker sits before the rule **name**, not next to the
category badge.
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