feat(postcodes/CO): bulk-import 3,676 Colombia postcodes via 4-72 (#1039)

[dr5hn]

Summary

Adds 3,676 Colombia postcodes spanning all 33 DANE departments,
sourced from the official 4-72 (Servicios Postales Nacionales)
catalogue distributed via the JohaAlarcon/Load_postal_code mirror.

• Coverage: 100% department resolution (33/33 in states.json).
• Format: Canonical 6-digit national code (matches
  ^(\d{6})$); a handful of source rows ship with a missing or
  spurious leading zero and are normalised on import.

Source & licence

• Source URL: https://raw.githubusercontent.com/JohaAlarcon/Load_postal_code/master/C_digos_Postales_Nacionales.csv
• Origin: 4-72 / Servicios Postales Nacionales (Colombian postal
  operator). The catalogue is published for free public reference;
  attribution recorded in the source column of every row.
• Each row: "source": "4-72-via-JohaAlarcon"

How it works

• DANE department code (2-digit) is mapped to CSC's 3-letter iso2
  via a hand-curated 33-entry table (e.g. 05 -> ANT, 11 -> DC, 88 -> SAP).
• The free-text limite column carries street-level boundary
  descriptions (and arrives mojibake-encoded); intentionally not used
  as locality_name.

Validation

• python3 -m py_compile clean.
• 100% of 3,676 codes match country.postal_code_regex.
• 100% of records resolve a valid state_id whose
  country_id == 48 and whose iso2 matches state_code.
• No auto-managed fields (id, created_at, updated_at,
  flag).

Test plan

• Importer compiles and runs on a clean checkout.
• Cross-reference validator passes (regex + FK + state_code agreement).
• Idempotent merge verified.
• CI pipeline green.

Refs #1039.

🤖 Generated with Claude Code

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CSC Validation Report

PR Format

• ✅ Description provided
• ✅ Data source linked
• ✅ Issue linked (recommended for data changes)
• ✅ Justification / context provided

Labels applied: data:postcodes, large-contribution

⚠️ Large Contribution

This PR contains 3676 records. Large contributions require manual review.

Schema Validation (3676 records)

✅ All records passed validation

Cross-Reference Validation

✅ 7352 reference(s) verified

Source URL Verification

✅ 2 source URL(s) accessible

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✅ All checks passed | Status: Ready for review