fix: restore .npmrc and document it in CLAUDE.md

The local .npmrc with ignore-scripts=false is required to override
global npm settings that disable build scripts.

Added rule to CLAUDE.md: DO NOT DELETE OR MODIFY this file.

Author: JohannesHoppe

CLAUDE.md

@@ -14,6 +14,8 @@ All development commands must be run from the `src` directory:
 cd src
 ```
 
+**IMPORTANT:** The `src/.npmrc` file contains `ignore-scripts=false` to override global npm settings. **DO NOT DELETE OR MODIFY this file** - it's required for build scripts to run.
+
 ### Build
 ```bash
 npm run build

src/.npmrc

@@ -0,0 +1 @@
+ignore-scripts=false