Add anipy-cli download fallback

Add an optional config toggle that retries failed ani-cli downloads with anipy-cli, expose fallback runtime status in the config page, and update release docs and tests for the new behavior.

http_handler.py

@@ -21,6 +21,7 @@ from urllib.parse import parse_qs, unquote, urlencode, urlparse, urlunparse
 
 from app_support import (
     ANI_CLI,
+    ANIPY_CLI,
     APP_NAME,
     CHANGELOG_FILE,
     CLIENT_DISCONNECT_ERRORS,
@@ -32,6 +33,7 @@ from app_support import (
     debug_enabled,
     debug_log,
     load_project_text_file,
+    cli_executable_exists,
     normalize_config,
     path_is_within_roots,
     remote_access_allowed,
@@ -87,7 +89,8 @@ def build_handler_class(context):
 def dependency_status():
     checks = ["curl", "sed", "grep", "openssl", "fzf", "aria2c", "ffmpeg", "yt-dlp"]
     result = {name: bool(shutil.which(name)) for name in checks}
-    result["ani-cli"] = bool(shutil.which(ANI_CLI) or (Path(ANI_CLI).exists() and os.access(ANI_CLI, os.X_OK)))
+    result["ani-cli"] = cli_executable_exists(ANI_CLI)
+    result["anipy-cli"] = cli_executable_exists(ANIPY_CLI)
     return result
 
 
@@ -166,6 +169,22 @@ def installed_ani_cli_version():
     return version or "Unavailable"
 
 
+@lru_cache(maxsize=1)
+def installed_anipy_cli_version():
+    try:
+        completed = subprocess.run(
+            [ANIPY_CLI, "--version"],
+            check=True,
+            capture_output=True,
+            text=True,
+            timeout=6,
+        )
+    except (OSError, subprocess.SubprocessError):
+        return "Unavailable"
+    version = str(completed.stdout or completed.stderr or "").strip()
+    return version or "Unavailable"
+
+
 class Handler(BaseHTTPRequestHandler):
     server_version = "AniCliWeb/1.0"
     remote_session_cookie_name = "ani_cli_web_session"
@@ -535,7 +554,14 @@ class Handler(BaseHTTPRequestHandler):
             elif parsed.path == "/api/config":
                 self.json(sanitize_public_config(Handler._context(self).get_config_snapshot()))
             elif parsed.path == "/api/version":
-                self.json({"name": APP_NAME, "version": VERSION, "ani_cli_version": installed_ani_cli_version()})
+                self.json(
+                    {
+                        "name": APP_NAME,
+                        "version": VERSION,
+                        "ani_cli_version": installed_ani_cli_version(),
+                        "anipy_cli_version": installed_anipy_cli_version(),
+                    }
+                )
             elif parsed.path == "/api/changelog":
                 self.json({"content": load_project_text_file(CHANGELOG_FILE, default="Changelog unavailable.")})
             elif parsed.path == "/api/dependencies":