Add WaterSheep to open models

[SamratDuttaOfficial]

Adds WaterSheep to open models: one entry in data/projects.json, with the three READMEs regenerated by npm run catalog:readmes and the project count in validate.test.mjs moved from 228 to 229.

• Repository: https://github.com/SamratDuttaOfficial/WaterSheep (Apache-2.0, Python)
• Primary source: the README at a fixed commit, https://github.com/SamratDuttaOfficial/WaterSheep/blob/3ccf02b3839fd2d72e6fb29750488010c7d76360/README.md
• Permalink to the Jev-compatible part: the /v1/systemone handler, https://github.com/SamratDuttaOfficial/WaterSheep/blob/3ccf02b3839fd2d72e6fb29750488010c7d76360/watersheep/cli.py#L24-L31
• The decision: it picks among the options a caller defines and returns a probability for each. The caller's code then acts on the answer or holds it back below a threshold, the same way a Jev client does.

It has 3 stars today, under your 50-star floor, so the floor check in catalogue metadata is explicit fails. I didn't touch that assertion; it's your call whether it fits. I'm the author.