[1/4] Migrate from CountryEnumable to ISO3166::Country Alpha2

[manuthecoder]

🔁 Migrate from CountryEnumable to ISO3166::Country Alpha2 (1/4)

🧠 Context

We're deprecating our custom CountryEnumable::country_enum_list (which maps countries to integers) in favor of ISO3166::Country, which uses standard alpha2 codes ("US", "IN", etc.). This shift will simplify country handling across the codebase and reduce redundancy.

This is Step 1 of a 4 part migration process

---

✅ Changes in this PR

• Adds new country_alpha2 (string) columns via migration:
  • events.country_alpha2
  • wires.country_alpha2
• Adds before_save hooks to auto-populate country_alpha2 based on existing:
  • event.country
  • wire.recipient_country
• Removes:
  • include CountryEnumable
  • has_country_enum from the Event model to begin decoupling from the legacy enum system.

---

Overview

1. Add country_alpha2 columns + save hooks (this PR ✅
2. Backfill alpha2 values from existing integer data
3. Update app logic to use country_alpha2 (UI, filters, validations)
4. Drop old enum fields + delete CountryEnumable

---

Existing behavior using event.country or wire.recipient_country should remain intact for now