feat: Simplify keystore decoding process in build workflow using inline Python script

.gitea/workflows/build-apk.yml

@@ -2,6 +2,8 @@ name: Build Android APK
 
 on:
   push:
+    tags:
+      - "v*"
   workflow_dispatch:
     inputs:
       release_tag:
@@ -85,58 +87,7 @@ jobs:
           if [ -n "${ANDROID_KEYSTORE_BASE64}" ] && [ -n "${ANDROID_KEYSTORE_PASSWORD}" ] && [ -n "${ANDROID_KEY_ALIAS}" ] && [ -n "${ANDROID_KEY_PASSWORD}" ]; then
             echo "Preparing release keystore from secrets"
 
-            if ! python3 - <<'PY'
-import base64
-import os
-import re
-import sys
-
-s = os.environ.get("ANDROID_KEYSTORE_BASE64", "")
-if not s:
-    print("ANDROID_KEYSTORE_BASE64 is empty")
-    sys.exit(1)
-
-# Normalize common copy/paste formats.
-s = s.strip().strip('"').strip("'")
-s = s.replace("\\n", "")
-s = re.sub(r"^data:[^,]*,", "", s)
-s = re.sub(r"\s+", "", s)
-
-if not s:
-    print("ANDROID_KEYSTORE_BASE64 is empty after normalization")
-    sys.exit(1)
-
-def try_decode(value: str, urlsafe: bool, validate: bool):
-    value = value + ("=" * (-len(value) % 4))
-    if urlsafe:
-        value = value.replace("-", "+").replace("_", "/")
-    return base64.b64decode(value, validate=validate)
-
-decoded = None
-errors = []
-for urlsafe in (False, True):
-    for validate in (True, False):
-        try:
-            decoded = try_decode(s, urlsafe=urlsafe, validate=validate)
-            if decoded:
-                break
-        except Exception as e:
-            errors.append(str(e))
-    if decoded:
-        break
-
-if not decoded:
-    print("Failed to decode ANDROID_KEYSTORE_BASE64")
-    print("Tip: generate with: base64 < release.jks | tr -d '\\n'")
-    if errors:
-        print("Last decode error:", errors[-1])
-    sys.exit(1)
-
-with open("android/release.keystore", "wb") as f:
-    f.write(decoded)
-
-print(f"Decoded keystore bytes: {len(decoded)}")
-PY
+            if ! python3 -c "import base64,os,re,sys; s=os.environ.get('ANDROID_KEYSTORE_BASE64',''); s=s.strip().strip(chr(34)).strip(chr(39)); s=s.replace('\\n',''); s=re.sub(r'^data:[^,]*,','',s); s=re.sub(r'\\s+','',s); s=s + ('=' * (-len(s) % 4)); (print('ANDROID_KEYSTORE_BASE64 is empty after normalization'), sys.exit(1)) if not s else None; d=base64.b64decode(s, validate=False); open('android/release.keystore','wb').write(d); print('Decoded keystore bytes:', len(d))"
             then
               echo "Keystore decoding failed"
               exit 1