Nationwide Discussions: tabbed dialog for WPC, SPC, NHC, CPC discussions

[Orinks]

Overview

Bring back the Nationwide Discussions feature from the legacy app. When a "Nationwide" pseudo-location is selected, the View Discussion button opens a tabbed dialog showing national weather discussions from multiple NWS centers.

Implementation

NationalDiscussionService

• Fetch discussions via NWS API (api.weather.gov/products/types/) for PMD (WPC), SWO (SPC), QPF
• Fall back to BeautifulSoup scraping for NHC tropical outlooks and CPC extended outlooks
• Rate limiting and retry logic (existing scraper pattern)

Nationwide pseudo-location

• Add "Nationwide" to locations list (special entry, no lat/lon)
• When selected, View Discussion opens the national discussion dialog instead of local AFD
• Config manager support for the special location

Tabbed Discussion Dialog

• WPC tab: Short Range (Days 1-3), Medium Range (3-7), Extended (8-10), QPF Discussion
• SPC tab: Day 1, Day 2, Day 3 Convective Outlooks
• NHC tab (June-November only): Atlantic Outlook, East Pacific Outlook
• CPC tab: 6-10 Day Outlook, 8-14 Day Outlook
• All read-only text controls with full keyboard navigation
• Accessible: labeled controls, screen reader friendly

NWS API Product Codes

• PMD - Prognostic Meteorological Discussion (WPC short/medium/extended)
• SWO - Severe Storm Outlook Narrative (SPC Day 1/2/3)
• QPF - Quantitative Precipitation Forecast
• AFD - Area Forecast Discussion (local, already implemented)

Scraping needed (no API)

• NHC Tropical Weather Outlook (nhc.noaa.gov)
• CPC 6-10 and 8-14 Day Outlooks (cpc.ncep.noaa.gov)

Notes

• No AI features required; this is a standalone read-only discussion viewer
• BeautifulSoup already in dependencies
• Existing national_discussion_scraper.py can be extended
• Branch: feature/nationwide-discussions
• Target: dev branch

[Orinks]

Implemented in PR #293. Nationwide weather discussions with WPC, SPC, NHC, CPC tabs and AI summarization.