Move off dead-end Node 25 to Node 26

- Bump `mise.toml` `node` pin from `25` to `26` (CI reads it via `jdx/mise-action`); no other Node pins exist (no `.nvmrc`, `setup-node`, or `engines.node`).
- Add `@types/node@^26` as an explicit `devDependency` (resolves to `26.0.1`). It was previously only an optional transitive peer of `vite`/`vitest` resolved at `25.x`; `pnpm dedupe` prunes that optional peer, which left `svelte-check` unable to find `node:` builtins used in `vite.config.ts` and the tests. Declaring it explicitly makes the node-types requirement stable and aligns it with Node 26.
- Refresh `pnpm-lock.yaml` via `pnpm install` + `pnpm dedupe`.

All checks green: `gofmt`, `go vet`, `staticcheck`, Go tests, `pnpm audit`, `prettier`, `knip`, `eslint`, `svelte-check`, `vitest` (163 tests).

Author: vdavid

mise.toml

@@ -1,4 +1,4 @@
 [tools]
-node = "25"
+node = "26"
 pnpm = "11"
 go = "1.25"

package.json

@@ -25,6 +25,7 @@
         "@sveltejs/kit": "^2.58.0",
         "@sveltejs/vite-plugin-svelte": "^7.0.0",
         "@tailwindcss/vite": "^4.2.4",
+        "@types/node": "^26",
         "concurrently": "9.2.1",
         "eslint": "^10.2.1",
         "eslint-plugin-svelte": "^3.17.1",