Feature: Marine Mode (coastal essentials only) #323
Description
Problem
Marine support exists in pieces, but there isn't a focused, user-facing coastal weather mode.
Proposal
Add a lightweight Marine Mode focused on essentials (not a full marine suite):
- marine zone forecast summary
- wind/wave highlights
- marine advisories/warnings
Why
Coastal users get practical marine context without adding heavy scope (charts/maps/nav tooling).
Scope (Phase 1)
- NWS marine zone forecast retrieval + presentation
- concise marine conditions section
- marine advisory surface in alerts view
Out of Scope
- Interactive maps/radar overlays
- boating/navigation route planning
Acceptance Criteria
- Marine mode can be enabled per location/context
- Marine forecast summary renders in accessible text and HTML fallback
- Marine advisories are surfaced and readable by screen readers
- Tests for parser/presenter coverage