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>

src/tools/schematic.ts

@@ -1152,9 +1152,9 @@ Note: operates on .kicad_sch files only. To modify a PCB footprint use edit_comp
   // Generate netlist
   server.tool(
     "generate_netlist",
-    "Generate a netlist from the schematic",
+    "Return a structured JSON netlist from the schematic — component list (reference, value, footprint) and net list (net name with all connected component/pin pairs). Use this to inspect or verify connectivity within the conversation. Does not write any file. To export a netlist file in Spice, KiCad XML, Cadstar, or OrcadPCB2 format, use export_netlist instead.",
     {
-      schematicPath: z.string().describe("Path to the schematic file"),
+      schematicPath: z.string().describe("Absolute path to the .kicad_sch schematic file"),
     },
     async (args: { schematicPath: string }) => {
       const result = await callKicadScript("generate_netlist", args);