feat: implement REST API for program-model component

[evandowning]

This PR implements a comprehensive REST API for the program-model component to improve isolation between services.

Changes

• Add FastAPI server with endpoints for all CodeQuery operations
• Create HTTP client and compatibility layer for seamless migration
• Update patcher and seed-gen to use REST API instead of direct execution
• Remove codequery/cscope dependencies from Dockerfiles
• Move harness discovery functions to program-model component
• Add comprehensive unit tests and API documentation
• Provide CLI script for starting the API server

Resolves #116

🤖 Generated with Claude Code

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TODOs:

• [x] Run make test
• [x] Run libpng challenge
• [ ] Confirm modified patcher and seed-gen unit tests make sense.
• [x] Merge #148 into main and rebase