Fix grammar: correct 'PydanticAI' product name (no space)

[lunar-me]

Summary

This PR fixes a grammar issue in README.md (line 44).

Problem

"Pydantic AI" should be "PydanticAI" (one word). The official product name as used in their documentation and PyPI package has no space.

Fix

Changed:

Pydantic AI

To:

PydanticAI

Type of Change

• Documentation fix (grammar, spelling)
• Code change
• Breaking change

Checklist

• Documentation files only
• No code changes
• Fix verified against original text

[davidmckayv]

Thanks for looking at this, but the README is already correct and this would take it backwards.

The product renamed. Its own documentation heads the page # Pydantic AI and opens "Pydantic AI is the Python AI SDK" — with the space. PydanticAI is the pre-rename spelling, so this change restores an obsolete name.

Closing on the merits rather than the mechanics. Genuinely appreciate the other grammar fixes you sent; #170, #171 and #200 are real errors and are going in.