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/datasheet.ts

@@ -0,0 +1,123 @@
+/**
+ * Datasheet tools for KiCAD MCP server
+ *
+ * Enriches KiCAD schematic symbols with LCSC datasheet URLs.
+ * URL schema: https://www.lcsc.com/datasheet/<LCSC#>.pdf (no API key required)
+ */
+
+import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { z } from "zod";
+
+export function registerDatasheetTools(
+  server: McpServer,
+  callKicadScript: Function,
+) {
+  // ── enrich_datasheets ──────────────────────────────────────────────────────
+  server.tool(
+    "enrich_datasheets",
+    `Fill in missing Datasheet URLs in a KiCAD schematic using LCSC part numbers.
+
+For every placed symbol that has:
+  • (property "LCSC" "C123456") set
+  • (property "Datasheet" "~") or empty
+
+Sets the Datasheet field to:
+  https://www.lcsc.com/datasheet/C123456.pdf
+
+The URL is then visible in KiCAD's footprint browser, symbol properties dialog,
+and any tool that reads the standard KiCAD Datasheet field.
+No API key or internet lookup required – the URL is constructed directly.
+
+Use dry_run=true to preview changes without writing.`,
+    {
+      schematic_path: z
+        .string()
+        .describe("Path to the .kicad_sch file to enrich"),
+      dry_run: z
+        .boolean()
+        .optional()
+        .default(false)
+        .describe(
+          "If true, show what would be changed without writing to disk (default: false)",
+        ),
+    },
+    async (args: { schematic_path: string; dry_run?: boolean }) => {
+      const result = await callKicadScript("enrich_datasheets", args);
+      if (result.success) {
+        const lines: string[] = [];
+
+        if (args.dry_run) {
+          lines.push(`[DRY RUN] Schematic: ${result.schematic}\n`);
+        } else {
+          lines.push(`Schematic: ${result.schematic}\n`);
+        }
+
+        lines.push(`✓ Updated:         ${result.updated}`);
+        lines.push(`  Already set:     ${result.already_set}`);
+        lines.push(`  No LCSC number:  ${result.no_lcsc}`);
+        lines.push(`  No field:        ${result.no_datasheet_field}`);
+
+        if (result.details && result.details.length > 0) {
+          lines.push("\nComponents updated:");
+          for (const d of result.details) {
+            lines.push(`  ${d.reference.padEnd(6)} ${d.lcsc.padEnd(12)} → ${d.url}`);
+          }
+        }
+
+        if (result.updated === 0 && !args.dry_run) {
+          lines.push(
+            "\nNo changes needed – all LCSC components already have a Datasheet URL.",
+          );
+        }
+
+        return { content: [{ type: "text", text: lines.join("\n") }] };
+      }
+      return {
+        content: [
+          {
+            type: "text",
+            text: `Failed to enrich datasheets: ${result.message || "Unknown error"}`,
+          },
+        ],
+      };
+    },
+  );
+
+  // ── get_datasheet_url ──────────────────────────────────────────────────────
+  server.tool(
+    "get_datasheet_url",
+    `Get the LCSC datasheet URL for a component by LCSC number.
+
+Returns the direct PDF URL and product page URL.
+No network request – URL is constructed from the LCSC number alone.
+
+Example: get_datasheet_url("C179739")
+→ https://www.lcsc.com/datasheet/C179739.pdf`,
+    {
+      lcsc: z
+        .string()
+        .describe(
+          'LCSC part number, with or without "C" prefix (e.g. "C179739" or "179739")',
+        ),
+    },
+    async (args: { lcsc: string }) => {
+      const result = await callKicadScript("get_datasheet_url", { lcsc: args.lcsc });
+      if (result.success) {
+        const lines = [
+          `LCSC: ${result.lcsc}`,
+          `Datasheet PDF:  ${result.datasheet_url}`,
+          `Product page:   ${result.product_url}`,
+        ];
+        return { content: [{ type: "text", text: lines.join("\n") }] };
+      }
+      return {
+        content: [
+          {
+            type: "text",
+            text: `Invalid LCSC number: ${args.lcsc}`,
+          },
+        ],
+      };
+    },
+  );
+}