feat: Add template spell picker from spells.yml; polish spell table

- Add yaml-loader; import data/spells.yml at build time
- Add SpellTemplate/SpellsFile types to globals.d.ts
- Add 'Add Template Spell' button that opens a modal picker pre-filling
  all spell fields from the YAML data
- Move spell data files into data/ directory
- Split spell rows into inputs row + full-width notes row (colspan=6)
- Shrink delete column to fit-content; bold spell name input
- Add class column to spell table; change MP cost to free-text input
- Auto-resize spell notes textarea on load and on input
- Add 10px padding between spells for visual separation

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

package-lock.json

@@ -24,7 +24,8 @@
         "typescript": "^6.0.3",
         "webpack": "^5.107.2",
         "webpack-cli": "^7.0.3",
-        "webpack-dev-server": "^5.2.4"
+        "webpack-dev-server": "^5.2.4",
+        "yaml-loader": "^0.9.0"
       }
     },
     "node_modules/@babel/code-frame": {
@@ -4243,6 +4244,13 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/javascript-stringify": {
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/javascript-stringify/-/javascript-stringify-2.1.0.tgz",
+      "integrity": "sha512-JVAfqNPTvNq3sB/VHQJAFxN/sPgKnsKrCwyRt15zwNCdrMMJDdcEOdubuy+DuJYYdm0ox1J4uzEuYKkN+9yhVg==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/jest-regex-util": {
       "version": "30.4.0",
       "resolved": "https://registry.npmjs.org/jest-regex-util/-/jest-regex-util-30.4.0.tgz",
@@ -7233,6 +7241,36 @@
       "dev": true,
       "license": "ISC"
     },
+    "node_modules/yaml": {
+      "version": "2.9.0",
+      "resolved": "https://registry.npmjs.org/yaml/-/yaml-2.9.0.tgz",
+      "integrity": "sha512-2AvhNX3mb8zd6Zy7INTtSpl1F15HW6Wnqj0srWlkKLcpYl/gMIMJiyuGq2KeI2YFxUPjdlB+3Lc10seMLtL4cA==",
+      "dev": true,
+      "license": "ISC",
+      "bin": {
+        "yaml": "bin.mjs"
+      },
+      "engines": {
+        "node": ">= 14.6"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/eemeli"
+      }
+    },
+    "node_modules/yaml-loader": {
+      "version": "0.9.0",
+      "resolved": "https://registry.npmjs.org/yaml-loader/-/yaml-loader-0.9.0.tgz",
+      "integrity": "sha512-N0bPfDR42qCruELfmpF6Q8XnDu1elTULGjvVn7u6rsfDa8WhlmJbjXQRh+x5TGmpOqw8R9qfiUgc3aKP+8Hd4w==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "javascript-stringify": "^2.0.1",
+        "yaml": "^2.0.0"
+      },
+      "engines": {
+        "node": ">= 20"
+      }
+    },
     "node_modules/yocto-queue": {
       "version": "0.1.0",
       "resolved": "https://registry.npmjs.org/yocto-queue/-/yocto-queue-0.1.0.tgz",