Fix project root path calculation in version and update functions

- Correct path traversal from 4 to 3 levels up (server -> auracast -> src -> bumble-auracast)
- Add clarifying comments for path calculation
- Apply fix consistently across get_version(), check_update(), and system_update() functions

src/auracast/server/multicast_server.py

@@ -903,7 +903,8 @@ async def system_reboot():
 async def get_version():
     """Get the current software version (git tag or commit)."""
     try:
-        project_root = os.path.abspath(os.path.join(os.path.dirname(__file__), '..', '..', '..', '..'))
+        # server -> auracast -> src -> bumble-auracast (3 levels up)
+        project_root = os.path.abspath(os.path.join(os.path.dirname(__file__), '..', '..', '..'))
         
         # Try to get the current tag
         proc = await asyncio.create_subprocess_exec(
@@ -937,7 +938,8 @@ async def get_version():
 async def check_update():
     """Check for available updates by comparing current version with latest release tag."""
     try:
-        project_root = os.path.abspath(os.path.join(os.path.dirname(__file__), '..', '..', '..', '..'))
+        # server -> auracast -> src -> bumble-auracast (3 levels up)
+        project_root = os.path.abspath(os.path.join(os.path.dirname(__file__), '..', '..', '..'))
         
         # Fetch all tags and refs from origin
         proc = await asyncio.create_subprocess_exec(
@@ -993,8 +995,8 @@ async def system_update():
         except Exception:
             pass
 
-        # Project root is 4 levels up from this file: server -> auracast -> src -> bumble-auracast
-        project_root = os.path.abspath(os.path.join(os.path.dirname(__file__), '..', '..', '..', '..'))
+        # server -> auracast -> src -> bumble-auracast (3 levels up)
+        project_root = os.path.abspath(os.path.join(os.path.dirname(__file__), '..', '..', '..'))
 
         # 1. Fetch and checkout the latest tag from the release branch
         # First fetch all tags and the release branch