feat: datasheet tools + fix missing delete_schematic_component

New tools - datasheet:
- get_datasheet_url: construct LCSC datasheet PDF URL + product page URL
  without any API key (URL schema: https://www.lcsc.com/datasheet/<C#>.pdf)
- enrich_datasheets: scan .kicad_sch, write LCSC datasheet URL into every
  symbol that has an LCSC property but an empty Datasheet field; supports
  dry_run=true for preview; text-based implementation (no skip writes)
  Implementation: python/commands/datasheet_manager.py

New tool - schematic:
- delete_schematic_component: remove a placed symbol from a .kicad_sch file
  by reference designator (e.g. R1, U3)

Bug fix - delete_schematic_component (two separate root causes):
1. No MCP tool named delete_schematic_component was registered at all.
   Any delete-symbol request fell through to the PCB-only delete_component
   tool which searches pcbnew.BOARD and always returned 'Component not found'
   for schematic symbols.
2. component_schematic.py::remove_component() still used skip for writes.
   PR #40 rewrote DynamicSymbolLoader (add path) to avoid skip-induced
   schematic corruption, but the delete path was not touched by that PR.

Fix: _handle_delete_schematic_component in kicad_interface.py uses direct
text manipulation with parenthesis-depth tracking (same technique as PR #40),
bypassing component_schematic.py entirely. Error message explicitly guides
users: 'use delete_component for PCB footprints'.

Files changed:
- python/commands/datasheet_manager.py (new)
- src/tools/datasheet.ts (new)
- python/kicad_interface.py: 3 new handlers + dispatch entries
- src/tools/schematic.ts: delete_schematic_component tool
- src/server.ts: registerDatasheetTools import + call
- src/tools/index.ts: export registerDatasheetTools
- CHANGELOG.md: document all above

src/tools/index.ts

@@ -1,15 +1,16 @@
-/**
- * Tools index for KiCAD MCP server
- * 
- * Exports all tool registration functions
- */
-
-export { registerProjectTools } from './project.js';
-export { registerBoardTools } from './board.js';
-export { registerComponentTools } from './component.js';
-export { registerRoutingTools } from './routing.js';
-export { registerDesignRuleTools } from './design-rules.js';
-export { registerExportTools } from './export.js';
-export { registerSchematicTools } from './schematic.js';
-export { registerLibraryTools } from './library.js';
-export { registerUITools } from './ui.js';
+/**
+ * Tools index for KiCAD MCP server
+ *
+ * Exports all tool registration functions
+ */
+
+export { registerProjectTools } from "./project.js";
+export { registerBoardTools } from "./board.js";
+export { registerComponentTools } from "./component.js";
+export { registerRoutingTools } from "./routing.js";
+export { registerDesignRuleTools } from "./design-rules.js";
+export { registerExportTools } from "./export.js";
+export { registerSchematicTools } from "./schematic.js";
+export { registerLibraryTools } from "./library.js";
+export { registerUITools } from "./ui.js";
+export { registerDatasheetTools } from "./datasheet.js";