feat(postcodes/SE): bulk-import 16,361 codes via SE community mirror (#1039) (#1442)

Adds Swedish postcodes via the zegl/sweden-zipcode community CSV.

1. bin/scripts/sync/import_sweden_postcodes.py — pipeline reading
   Zip,City CSV. Formats codes in '### ##' form to match the SE regex.

2. contributions/postcodes/SE.json — 16k+ records.

state_id is null on every row: Swedish postcodes are organised by
sorting-route geography, not administrative county. Without a
kommune-postcode crosswalk the source CSV does not include, no
reliable state assignment is possible. State backfill remains a
follow-up using Skatteverket open ortsdata.

License & attribution
- Mirror: github.com/zegl/sweden-zipcode
- Each row: source: 'se-zipcode'

Refs: #1039

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: dr5hn

bin/scripts/sync/import_sweden_postcodes.py

@@ -0,0 +1,122 @@
+#!/usr/bin/env python3
+"""Sweden -> contributions/postcodes/SE.json importer for issue #1039.
+
+Source data
+-----------
+The community-maintained ``zegl/sweden-zipcode`` archive redistributes a
+plain Zip,City CSV covering 16,393 Swedish postcodes.
+
+  https://github.com/zegl/sweden-zipcode
+
+What this script does
+---------------------
+1. Reads sweden-zipcode.csv (UTF-8, header: Zip,City)
+2. Picks one canonical record per unique zip (first city alphabetically
+   when multiple rows exist for one code)
+3. Formats codes in the canonical "### ##" form expected by
+   countries.postal_code_regex (^(?:SE)?\\d{3}\\s\\d{2}$)
+4. Writes contributions/postcodes/SE.json
+
+Why state_id is null
+--------------------
+Swedish postcodes were assigned by sorting-route geography rather than
+by administrative county boundaries, so there is no reliable prefix-to-
+county mapping. The source CSV has no kommune column either. State
+resolution would require a separate kommune-postcode crosswalk that
+isn't redistributable. Records ship with country_id only; state_id can
+be backfilled in a follow-up PR once a clean kommune crosswalk is wired
+in (e.g. via Skatteverket's open ortsdata).
+
+License & attribution
+---------------------
+- Mirror: github.com/zegl/sweden-zipcode (community redistribution)
+- Each row: source: "se-zipcode"
+"""
+
+from __future__ import annotations
+
+import argparse
+import csv
+import json
+import sys
+from pathlib import Path
+from typing import Dict, List
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--input", default="/tmp/se_zipcodes.csv")
+    parser.add_argument("--dry-run", action="store_true")
+    args = parser.parse_args()
+
+    src = Path(args.input)
+    if not src.exists():
+        print(f"ERROR: input not found: {src}", file=sys.stderr)
+        return 2
+
+    project_root = Path(__file__).resolve().parents[3]
+    countries = json.load((project_root / "contributions/countries/countries.json").open(encoding="utf-8"))
+    se = next((c for c in countries if c.get("iso2") == "SE"), None)
+    if se is None:
+        print("ERROR: SE not in countries.json", file=sys.stderr)
+        return 2
+    print(f"Country: Sweden (id={se['id']})")
+
+    by_code: Dict[str, List[str]] = {}
+    with src.open(encoding="utf-8", newline="") as f:
+        reader = csv.DictReader(f)
+        for row in reader:
+            zip_raw = (row.get("Zip") or "").strip()
+            city = (row.get("City") or "").strip()
+            if not zip_raw or not zip_raw.isdigit() or len(zip_raw) != 5:
+                continue
+            # Format ### ##
+            code = f"{zip_raw[:3]} {zip_raw[3:]}"
+            by_code.setdefault(code, []).append(city)
+
+    print(f"Unique zips: {len(by_code):,}")
+
+    records: List[dict] = []
+    for code in sorted(by_code):
+        cities = sorted(by_code[code], key=lambda c: c.upper())
+        record = {
+            "code": code,
+            "country_id": int(se["id"]),
+            "country_code": "SE",
+        }
+        if cities and cities[0]:
+            record["locality_name"] = cities[0]
+        record["type"] = "full"
+        record["source"] = "se-zipcode"
+        records.append(record)
+
+    print(f"Records: {len(records):,}")
+
+    if args.dry_run:
+        return 0
+
+    target = project_root / "contributions/postcodes/SE.json"
+    if target.exists():
+        with target.open(encoding="utf-8") as f:
+            existing = json.load(f)
+        seen = {(r["code"], (r.get("locality_name") or "").lower()) for r in existing}
+        merged = list(existing)
+        for r in records:
+            key = (r["code"], (r.get("locality_name") or "").lower())
+            if key not in seen:
+                merged.append(r)
+                seen.add(key)
+        merged.sort(key=lambda r: (r["code"], r.get("locality_name", "")))
+    else:
+        merged = sorted(records, key=lambda r: (r["code"], r.get("locality_name", "")))
+
+    with target.open("w", encoding="utf-8") as f:
+        json.dump(merged, f, ensure_ascii=False, indent=2)
+        f.write("\n")
+    size_kb = target.stat().st_size / 1024
+    print(f"\n[OK] Wrote {target.relative_to(project_root)} ({len(merged):,} rows, {size_kb:.0f} KB)")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())