Republish setup: fastlane + Forgejo CI, signing/version fixes, Play-policy link

- support_page: repoint comunes.org link to project page (Play re-approval)
- build.gradle: conditional release signing (debug fallback), versionCode/Name
  from pubspec, drop duplicate google-services plugin
- pubspec: version 1.10.0+10 (versionCode must exceed last uploaded)
- track AndroidManifest.xml (no secrets in it)
- fastlane: Appfile/Fastfile (deploy_play/deploy_metadata/promote_production) +
  Gemfile + es/en/gl store metadata
- .forgejo: ci.yml (analyze+test) + release.yml (tag v* -> signed AAB -> Play internal)
- README + RELEASE.md

android/app/build.gradle

@@ -12,9 +12,14 @@ if (localPropertiesFile.exists()) {
     }
 }
 
+// Release signing is opt-in: only load key.properties if it exists. Without it
+// (CI analyze/test jobs, contributors) builds fall back to debug signing.
 def keystorePropertiesFile = rootProject.file("key.properties")
 def keystoreProperties = new Properties()
-keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
+def hasReleaseKeystore = keystorePropertiesFile.exists()
+if (hasReleaseKeystore) {
+    keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
+}
 
 android {
     compileSdkVersion 36
@@ -29,23 +34,28 @@ android {
         applicationId "org.comunes.fires"
         minSdkVersion flutter.minSdkVersion
         targetSdkVersion 36
-        versionCode 9
-        versionName "1.9"
+        // versionCode/versionName come from pubspec.yaml (version: X.Y.Z+CODE)
+        // so a `v*` git tag maps the release version, matching the tane flow.
+        versionCode flutter.versionCode
+        versionName flutter.versionName
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
     }
 
     signingConfigs {
-        release {
-            keyAlias keystoreProperties['keyAlias']
-            keyPassword keystoreProperties['keyPassword']
-            storeFile file(keystoreProperties['storeFile'])
-            storePassword keystoreProperties['storePassword']
+        if (hasReleaseKeystore) {
+            release {
+                keyAlias keystoreProperties['keyAlias']
+                keyPassword keystoreProperties['keyPassword']
+                storeFile file(keystoreProperties['storeFile'])
+                storePassword keystoreProperties['storePassword']
+            }
         }
     }
 
     buildTypes {
         release {
-            signingConfig signingConfigs.release
+            // Sign with the release key when available, else debug (contributors/CI).
+            signingConfig hasReleaseKeystore ? signingConfigs.release : signingConfigs.debug
 
             minifyEnabled true
             shrinkResources true
@@ -83,5 +93,3 @@ dependencies {
 }
 
 apply plugin: 'com.google.gms.google-services'
-
-apply plugin: 'com.google.gms.google-services'