German stemmer vocabulary tests failing

[kljensen]

Issue

The German stemmer vocabulary tests are failing with mismatches between expected and actual output.

Root Cause

The German stemmer implementation doesn't fully match the official Snowball algorithm specification at https://snowballstem.org/algorithms/german/stemmer.html

What Needs to be Done

1. Review and correct all stemming steps against the official algorithm
2. Verify preprocess, step1, step2, step3, and postprocess functions
3. Ensure suffix removal rules match specification
4. Run vocabulary tests until they pass

Test Command

go test ./german_vocab -v

Related

This was introduced in the initial implementation of German stemmer.