fix: start hw_server explicitly before Vivado JTAG scan

Previously the TCL script relied on Vivado's connect_hw_server to
auto-start hw_server. On Windows this either never worked (hw_server
never shows in Task Manager) or hung indefinitely during Vivado's
slow batch-mode initialisation.

Root cause: hw_server was never started.

Changes:
- vitis_checker.py: add 'hw_server' to TOOL_ALIASES + get_hw_server_path()
- zynq_checker.py: start hw_server via Popen before Vivado, kill in finally
  - 2s sleep for port binding after start
  - timeout from config.step_timeouts.check_env (default bumped to 120s)
  - clean terminate/kill sequence in finally
- config_manager.py: check_env default 30 → 120s

src/vitis_checker.py

@@ -56,6 +56,7 @@ TOOL_ALIASES: dict[str, list[str]] = {
     "xsct": ["xsct"],
     "program_flash": ["program_flash"],
     "bootgen": ["bootgen"],
+    "hw_server": ["hw_server"],
 }
 
 # Product subdirectories under xilinx_root to scan (in preference order)
@@ -330,6 +331,24 @@ def get_vivado_path(vitis_path: str = "", xilinx_root: str = "") -> str | None:
     return _find_executable("vivado", vitis_path, platform.system().lower(), xilinx_root)
 
 
+def get_hw_server_path(vitis_path: str = "", xilinx_root: str = "") -> str | None:
+    """Find the hw_server executable (Xilinx hardware server).
+
+    hw_server must be running before Vivado/xsct can connect to the
+    JTAG chain. This finder searches the same Vitis/Vivado bin dirs.
+
+    Args:
+        vitis_path: Legacy Vitis installation directory.
+        xilinx_root: Xilinx root directory.
+
+    Returns:
+        Path to hw_server executable, or None.
+    """
+    return _find_executable(
+        "hw_server", vitis_path, platform.system().lower(), xilinx_root
+    )
+
+
 # ── Tool version detection ───────────────────────────────────────────