Fix tsx runtime dependency resolution

[0xble]

Problem

The qmd wrapper script uses --import tsx with a bare specifier, which Node.js resolves relative to the current working directory instead of the package installation directory. This causes ERR_MODULE_NOT_FOUND errors when tsx is not installed globally.

Additionally, tsx is currently listed as a devDependency, but it's required at runtime by the wrapper script.

Solution

This PR implements the fix recommended by analyzing the issue:

1. Move tsx to runtime dependencies - tsx is required at runtime, not just development
2. Fix wrapper script tsx resolution - Added find_tsx_loader() function that searches up from the package installation directory to find node_modules/tsx/dist/loader.mjs, working with both nested and hoisted node_modules layouts
3. Update documentation - Clarified in CLAUDE.md that:
   • Development can use Bun for package management and testing
   • Runtime requires Node.js >=22 due to better-sqlite3 incompatibility with Bun
   • The wrapper uses Node.js + tsx, not Bun

Changes

• package.json: Moved tsx from devDependencies to dependencies
• qmd wrapper: Added robust tsx loader resolution that works regardless of installation method
• CLAUDE.md: Updated to clarify Node.js runtime requirement vs Bun development usage

Testing

After these changes, qmd will work correctly when installed via:

• npm install -g @tobilu/qmd
• bun install -g @tobilu/qmd

Without requiring a separate global tsx installation.

Fixes the ERR_MODULE_NOT_FOUND error reported by users installing qmd.

[JannikWempe]

qmd is currently broken for me because of the mentioned issue.