Add safe manual location address editing

[stef-k]

Summary

• add responsive manual editing for all stored Location address fields
• preserve or clear provider provenance according to address and coordinate changes
• reject stale forms after provider enrichment publication without contacting a provider
• show established address-precision guidance and add an accessible Wayfarer GitHub footer link

Closes #560

Validation

• focused manual-edit/controller/view tests: 8 passed
• real PostgreSQL Repair incomplete provider-enriched location addresses safely #559 publication compatibility: 1 passed
• dotnet build --no-restore: passed with 0 warnings/errors
• LOC: no hard failures; the cohesive existing Location controller is 597 LOC
• Code Guard: REVIEW only, no FAIL/INCOMPLETE
• git diff --check: passed

UI evidence

Automated local startup was blocked because the reusable development database contains protected provider credentials that are unreadable with this checkout's current Data Protection key ring. The application correctly failed closed. No credentials or database state were altered and no bespoke harness was created. Razor/controller contract coverage verifies the responsive disclosure, conditional expansion, custom alerts, precision text, and safe footer link.

Migration

No database migration.