Initial commit: MKV → AVI web app (Docker + Keycloak OIDC)

- App FastAPI : recherche dans un dossier média, download original ou
  conversion en AVI Xvid (tone-mapping HDR→SDR, audio FR auto, MP3 stéréo)
- Auth Keycloak OIDC (Authlib) optionnelle
- 3 composes : app seule, stack local (keycloak.local), production (NPM)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

keycloak/realm-mkv2avi.json

@@ -0,0 +1,44 @@
+{
+  "realm": "mkv2avi",
+  "enabled": true,
+  "sslRequired": "none",
+  "registrationAllowed": false,
+  "loginTheme": "keycloak",
+  "clients": [
+    {
+      "clientId": "mkv2avi",
+      "name": "MKV → AVI",
+      "enabled": true,
+      "protocol": "openid-connect",
+      "publicClient": false,
+      "clientAuthenticatorType": "client-secret",
+      "secret": "mkv2avi-secret-change-me",
+      "standardFlowEnabled": true,
+      "directAccessGrantsEnabled": true,
+      "serviceAccountsEnabled": false,
+      "redirectUris": [
+        "http://localhost:8090/*",
+        "https://mkv2avi.maisongrondin.fr/*"
+      ],
+      "webOrigins": ["+"],
+      "attributes": {
+        "post.logout.redirect.uris": "http://localhost:8090/*##https://mkv2avi.maisongrondin.fr/*"
+      },
+      "defaultClientScopes": ["web-origins", "profile", "roles", "email"],
+      "fullScopeAllowed": true
+    }
+  ],
+  "users": [
+    {
+      "username": "alex",
+      "enabled": true,
+      "emailVerified": true,
+      "email": "alex@example.com",
+      "firstName": "Alex",
+      "lastName": "Grondin",
+      "credentials": [
+        { "type": "password", "value": "alex", "temporary": false }
+      ]
+    }
+  ]
+}