fix(schematics): handle PMC download countdown page and ZIP-wrapped schematics

The download pipeline was getting HTML instead of the binary file because
PMC's /download/schematic/ returns a countdown confirmation page. Added
downloadSchematic() that uses a full browser flow (project visit → download
page → extract static URL → capture file). Also added ZIP extraction via
adm-zip for schematics wrapped in ZIP archives.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

package-lock.json

@@ -9,6 +9,7 @@
       "version": "1.0.0",
       "dependencies": {
         "@modelcontextprotocol/sdk": "^1.27.1",
+        "adm-zip": "^0.5.16",
         "express": "^4.21.2",
         "minecraft-data": "^3.105.0",
         "playwright": "^1.58.2",
@@ -382,6 +383,15 @@
         "node": ">= 0.6"
       }
     },
+    "node_modules/adm-zip": {
+      "version": "0.5.16",
+      "resolved": "https://registry.npmjs.org/adm-zip/-/adm-zip-0.5.16.tgz",
+      "integrity": "sha512-TGw5yVi4saajsSEgz25grObGHEUaDrniwvA2qwSC060KfqGPdglhvPMA2lPIoxs3PQIItj2iag35fONcQqgUaQ==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=12.0"
+      }
+    },
     "node_modules/ajv": {
       "version": "8.18.0",
       "resolved": "https://registry.npmjs.org/ajv/-/ajv-8.18.0.tgz",