Update media-server: Add execution timing and improve script/callback execution UI

Backend improvements:
- Add execution_time tracking for script execution
- Add execution_time tracking for callback execution
- Add /api/callbacks/execute/{callback_name} endpoint for debugging callbacks

Frontend improvements:
- Fix duration display showing N/A for fast scripts (0 is falsy in JS)
- Increase duration precision to 3 decimal places (0.001s)
- Always show output section with "(no output)" message when empty
- Improve output formatting with italic gray text for empty output

Documentation:
- Add localization section to README
- Document available languages (English, Russian)
- Add guide for contributing new translations

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

media_server/routes/scripts.py

@@ -4,6 +4,7 @@ import asyncio
 import logging
 import re
 import subprocess
+import time
 from typing import Any
 
 from fastapi import APIRouter, Depends, HTTPException, status
@@ -33,6 +34,7 @@ class ScriptExecuteResponse(BaseModel):
     stdout: str = ""
     stderr: str = ""
     error: str | None = None
+    execution_time: float | None = None
 
 
 class ScriptInfo(BaseModel):
@@ -117,6 +119,7 @@ async def execute_script(
             exit_code=result["exit_code"],
             stdout=result["stdout"],
             stderr=result["stderr"],
+            execution_time=result.get("execution_time"),
         )
 
     except Exception as e:
@@ -143,8 +146,9 @@ def _run_script(
         working_dir: Working directory
 
     Returns:
-        Dict with exit_code, stdout, stderr
+        Dict with exit_code, stdout, stderr, execution_time
     """
+    start_time = time.time()
     try:
         result = subprocess.run(
             command,
@@ -154,22 +158,28 @@ def _run_script(
             text=True,
             timeout=timeout,
         )
+        execution_time = time.time() - start_time
         return {
             "exit_code": result.returncode,
             "stdout": result.stdout[:10000],  # Limit output size
             "stderr": result.stderr[:10000],
+            "execution_time": execution_time,
         }
     except subprocess.TimeoutExpired:
+        execution_time = time.time() - start_time
         return {
             "exit_code": -1,
             "stdout": "",
             "stderr": f"Script timed out after {timeout} seconds",
+            "execution_time": execution_time,
         }
     except Exception as e:
+        execution_time = time.time() - start_time
         return {
             "exit_code": -1,
             "stdout": "",
             "stderr": str(e),
+            "execution_time": execution_time,
         }