fix: add weather location fallbacks

[gzhang33]

Summary

• add a frontend location fallback that uses network-based approximate coordinates when browser geolocation fails
• keep approximate coordinates unsaved until the user explicitly saves them in settings
• geocode location_name on the backend when weather endpoints are called without stored coordinates

Testing

• npm test -- --run tests/location.test.ts
• npx tsc --noEmit
• docker compose exec -T -e TEST_DATABASE_URL=postgresql+asyncpg://wardrobe:4f5a5cb732900d2d7890d3bcb215f05268b2dce7e6188c2d56810cd8e9ccba91@postgres:5432/wardrobe_test backend pytest tests/test_weather_api.py
• manual verification in local containers for the weather flow

Notes

• .gitignore has local changes in the worktree and is intentionally excluded from this PR.

[Copilot]

Pull request overview

Adds fallback mechanisms so the weather flow can still work when precise geolocation (or stored coordinates) aren’t available, by using network-based approximation on the frontend and on-demand geocoding on the backend.

Changes:

• Frontend: introduce shared location helper utilities (+ tests) and update Settings to fall back to IP-based approximate coordinates when browser geolocation fails.
• Backend: add WeatherService.geocode_location_name() and update weather endpoints to geocode location_name when coordinates are missing (plus API tests).
• UX: improve user-facing messaging when exact geolocation fails and approximate data is used.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
frontend/tests/location.test.ts	Adds unit coverage for new location helper utilities.
frontend/lib/location.ts	Introduces helpers for resolving network location responses, reverse-geocode formatting, and geolocation error messaging.
frontend/app/dashboard/settings/page.tsx	Adds network-location fallback and refactors reverse geocoding + messaging in Settings.
backend/tests/test_weather_api.py	Adds API-level tests for geocoding fallback behavior and missing-location errors.
backend/app/services/weather_service.py	Adds a Nominatim geocoding helper for resolving location_name to coordinates.
backend/app/api/weather.py	Uses geocoding fallback in /weather/current and /weather/forecast when coordinates aren’t stored/provided.

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[gzhang33]

Validation update for latest branch push:

• Reviewed all Copilot review threads in the PR UI/API: 5/5 are resolved; no remaining unresolved review comment requests found.
• Cleaned up the geocoding JSON error handling so HTTP failures and invalid JSON responses are handled distinctly.
• Fixed the Settings page lint warning for the unitSystem dependency without resetting unsaved measurement edits on unit toggles.
• Backend local test environment prepared with Python 3.11.15 in backend/.venv and project test dependencies installed.
• Backend full suite: 292 passed via pytest -q.
• Backend coverage validation: 292 passed via pytest --cov=app --cov-report=xml.
• Frontend tests: 61 passed via npm test.
• Frontend lint: npm run lint passes; the PR-touched Settings warning is gone. Remaining warnings are pre-existing in unrelated files.

Note: agent.md remains untracked locally and was not added to the PR.

[Anyesh]

Thankyou for your PR 🙏🏽