[Design - Admin] Backcountry Reservation | Advisories and closures page

### Design work description and context:
The **Advisories and closures page** wasn't in the scope of DUP and thus is new, below are the core business requirements we need to cover when it comes to Backcountry:

- For advisories, please refer to
[Discussion: Alerts, advisories, and broadcasts](https://apps.nrs.gov.bc.ca/int/confluence/display/BCPRS/Discussion%3A+Alerts%2C+advisories%2C+and+broadcasts)
- For closures, to automate bulk modification of impacted bookings, refund of fees, and email notifications

### Acceptance Criteria:
- [ ] Designer collaborates with researcher to clarify requirements and develop solutions.
- [ ] Draft and iterate detailed designs in Figma with Dev/Rizzies feedback
- [ ] Update associated documentation in Confluence to keep alignment with designs
- [ ] Create dev ticket for refinement and implementation

### Dependencies:
- Related to: #318
- Blocked by
- Blocking

### Relevant documentation as reference:
- [Backcountry Registration Requirements (admin)](https://apps.nrs.gov.bc.ca/int/confluence/pages/viewpage.action?pageId=289186536)
- [Discussion: Financials & Refund Adjudication](https://apps.nrs.gov.bc.ca/int/confluence/pages/viewpage.action?pageId=298125062)

### Definition of Ready: Design ticket

- [ ] Acceptance criteria are included
- [ ] Relevant documentation to context is linked

### Definition of Done: Design ticket
- [ ] Designs are peer reviewed by another designer
- [ ] Designs are reviewed by developers
- [ ] Design is reiterated based on feedback, as needed
#### PO Review pipeline:
- [ ] Acceptance criteria are checked by Product Owner
- [ ] Approved by Product Owner

Start with related issue #318 and the linked discussions on alerts, advisories, broadcasts, registration requirements, and financials/refunds. Collaborate with research and development stakeholders, then create and iterate the Figma designs, update the linked Confluence documentation, and create the implementation refinement ticket; done means peer, developer, and Product Owner reviews are complete.

Written by the indexing model from the issue text.