fix: implement export_netlist handler and rewrite generate_netlist to use kicad-cli

export_netlist was returning "Unknown command" because no Python handler
existed. generate_netlist was timing out (30s) due to an O(nets × components
× pins) wire-graph algorithm with a new PinLocator instantiated per net.

Both handlers now delegate to `kicad-cli sch export netlist`:
- export_netlist: new handler; writes KiCad XML / Spice / Cadstar / OrcadPCB2
  to the caller-supplied outputPath. Added schematicPath parameter to the TS
  tool definition (was absent, making file export impossible).
- generate_netlist: replaces the slow wire-graph with kicad-cli + XML parse;
  returns the same {components, nets} JSON the TS handler already expected.

Also adds _find_kicad_cli_static() so both handlers share CLI discovery
without depending on ExportCommands (which requires a loaded pcbnew board).

Cleaned up generate_netlist schema in tool_schemas.py (removed outputPath and
format fields the handler never used), updated MCP tool descriptions and
SCHEMATIC_TOOLS_REFERENCE.md to clearly distinguish the two tools.

26 unit tests added covering parameter validation, subprocess mocking,
format mapping, XML→JSON parsing, and error/timeout propagation.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

python/schemas/tool_schemas.py

@@ -1654,24 +1654,20 @@ SCHEMATIC_TOOLS = [
     },
     {
         "name": "generate_netlist",
-        "title": "Generate Netlist",
-        "description": "Generates a netlist from the schematic showing all components and their net connections.",
+        "title": "Generate Netlist (JSON)",
+        "description": (
+            "Returns a structured JSON netlist from the schematic: component list "
+            "(reference, value, footprint) and net list (net name + all connected "
+            "component/pin pairs). Uses kicad-cli internally — requires a saved "
+            ".kicad_sch file. For writing to a file or exporting SPICE/Cadstar/OrcadPCB2 "
+            "format, use export_netlist instead."
+        ),
         "inputSchema": {
             "type": "object",
             "properties": {
                 "schematicPath": {
                     "type": "string",
-                    "description": "Path to schematic file",
-                },
-                "outputPath": {
-                    "type": "string",
-                    "description": "Optional path to save netlist file",
-                },
-                "format": {
-                    "type": "string",
-                    "enum": ["kicad", "json", "spice"],
-                    "description": "Netlist output format",
-                    "default": "json",
+                    "description": "Absolute path to the .kicad_sch schematic file",
                 },
             },
             "required": ["schematicPath"],