feat: accept ISO country codes for --region

jp, us, kr and gb were aliases but au was unknown, and the first
spelling offered for it was auto, which means world. Every territory
of the region tree now answers to its ISO 3166-1 code, in the build
scripts and in the installer, whose SHA-256 is pinned again.

scripts/region.py

@@ -64,7 +64,9 @@ _PARENT: dict[str, str] = {
 
 REGIONS: frozenset[str] = frozenset({WORLD} | set(REGION_TREE) | set(_PARENT))
 
-# Accepted on the CLI and for legacy profile values.
+# Accepted on the CLI and for legacy profile values. Every territory also
+# answers to its ISO 3166-1 code: `au` alone was unknown, and the closest
+# spelling offered first was `auto`, which means world.
 ALIASES: dict[str, str] = {
     "jp": "japan",
     "ntsc-j": "japan",
@@ -78,6 +80,30 @@ ALIASES: dict[str, str] = {
     "korea": "south-korea",
     "auto": WORLD,
     "gb": "uk",
+    "ca": "canada",
+    "br": "brazil",
+    "mx": "mexico",
+    "ar": "argentina",
+    "fr": "france",
+    "de": "germany",
+    "it": "italy",
+    "es": "spain",
+    "nl": "netherlands",
+    "pt": "portugal",
+    "gr": "greece",
+    "pl": "poland",
+    "ru": "russia",
+    "se": "sweden",
+    "no": "norway",
+    "dk": "denmark",
+    "fi": "finland",
+    "cn": "china",
+    "tw": "taiwan",
+    "hk": "hong-kong",
+    "sg": "singapore",
+    "in": "india",
+    "au": "australia",
+    "nz": "new-zealand",
 }