Add timeout parameter to metadata_server and chunk_server init/step functions

Unified the function signatures across all process types (metadata server,
chunk server, and simulation client) to accept an int *timeout parameter.
This provides consistency in the simulation framework and allows all
process types to control their wakeup times.

**Changes:**

**Headers (metadata_server.h, chunk_server.h):**
- Updated metadata_server_init() to accept int *timeout parameter
- Updated metadata_server_step() to accept int *timeout parameter
- Updated chunk_server_init() to accept int *timeout parameter
- Updated chunk_server_step() to accept int *timeout parameter

**Implementations (metadata_server.c, chunk_server.c):**
- Modified init functions to set *timeout = -1 (no timeout needed)
- Modified step functions to set *timeout = -1 (no timeout needed)
- Both server types currently don't require periodic wakeups, but the
  parameter allows for future timeout-based behavior

**System Integration (system.c):**
- Updated spawn_simulated_process() to declare timeout variable once
  and pass it to all process init functions uniformly
- Updated update_simulation() to declare timeout variable once and
  pass it to all process step functions uniformly
- Simplified control flow by removing special case for client timeout
  handling - now all process types use the same timeout logic
- Consolidated timeout-to-wakeup_time conversion after switch statements

**Benefits:**
- Consistent API across all process types
- Cleaner code with reduced duplication
- Future-proof for server timeout requirements
- All processes now managed uniformly by simulation framework

The simulation continues to run correctly with all process types
handling timeout parameter appropriately.

src/chunk_server.h

@@ -35,8 +35,8 @@ typedef struct {
     PendingDownloadList pending_download_list;
 } ChunkServer;
 
-int chunk_server_init(ChunkServer *state, int argc, char **argv, void **contexts, struct pollfd *polled);
+int chunk_server_init(ChunkServer *state, int argc, char **argv, void **contexts, struct pollfd *polled, int *timeout);
 int chunk_server_free(ChunkServer *state);
-int chunk_server_step(ChunkServer *state, void **contexts, struct pollfd *polled, int num_polled);
+int chunk_server_step(ChunkServer *state, void **contexts, struct pollfd *polled, int num_polled, int *timeout);
 
 #endif // CHUNK_SERVER_INCLUDED