fix: security hardening and code review improvements

- hls proxy now signs full URL instead of hostname only (SSRF)
- viewer token required to start session (prevents stats forgery and password bypass)
- weak SECRET_KEY placeholder replaced with REPLACE_ME, startup warning added
- api key auth drops query-string fallback, Bearer header only
- hls variant playlist DRM detection fetches first variant
- dash manifest DRM detection added
- android webview detection restricted to Telegram only
- privacy comment removed from ip hash (ip is stored in plaintext)
- csv export adds range filter (today/7d/30d/all), defaults to 30d
- analytics export button integrated as dropdown with range selection
- docker-compose placeholder defaults updated
- readme and readme.zh-cn updated for v1.2.0 changes

docker-compose.yml

@@ -10,8 +10,9 @@ services:
     ports:
       - "8085:8080"
     environment:
-      SECRET_KEY: "change-this-secret"
-      DATABASE_URL: "postgresql://streamhall:streamhall_pg_password@postgres:5432/streamhall"
+      # Generate with: openssl rand -hex 32
+      SECRET_KEY: "REPLACE_ME"
+      DATABASE_URL: "postgresql://streamhall:REPLACE_DB_PASSWORD@postgres:5432/streamhall"
       TZ: "UTC"
       RTMP_HOST: "srs"
       # Comma-separated list of video directories (optional label:path format)
@@ -29,7 +30,7 @@ services:
     environment:
       POSTGRES_DB: "streamhall"
       POSTGRES_USER: "streamhall"
-      POSTGRES_PASSWORD: "streamhall_pg_password"
+      POSTGRES_PASSWORD: "REPLACE_DB_PASSWORD"
       TZ: "UTC"
     volumes:
       - ./postgres-data:/var/lib/postgresql/data