Inline navigation to registration details and back to results (no PDFs)

### Drill-Through & Return
**As a** registry analyst,
**I want** to open a registration from the results table and return to the exact same point in the list,
**So that** I can review multiple candidates without re-running the search or losing my place.

### Context

#### Business Rules
- [ ] Registration details open in the **same tab** with a **Back to Results** action.
- [ ] Returning preserves all filters, sort order, pagination, and scroll position.
- [ ] Deep links include a **state token** so browser **Back** also restores context.

### Acceptance Criteria / Scenarios
- **GIVEN** I open registration **MH-12345** from page 2
**WHEN** I click **Back to Results**
**THEN** I return to page 2 with original filters, sort, and scroll intact.

- **GIVEN** I use the browser **Back** button
**THEN** the same preserved state applies.