refactor: Restructure Gadget prompt to reduce tech hallucination

[KaiserRuben]

Problem

The Gadget service was hallucinating technologies and missing actual dependencies, despite an
extensive 500+ line prompt. This led to inaccurate and unreliable outputs.

Solution

This pull request replaces the monolithic prompt with a structured 4-step verification workflow.
This new approach makes it structurally difficult for the model to claim a technology without
verifying its existence in the codebase.

The new workflow is as follows:

1. Map project structure: The model starts by listing the directory contents to understand the
   project layout.
2. Verify technologies: It then reads specific files to verify the presence of each technology.
3. Extract configuration: All relevant configuration is extracted from the verified files.
4. Validate build requirements: Finally, it validates the build requirements based on the
   extracted configuration.

Key Changes

• Reduced the prompt from ~500 to ~100 lines.
• Introduced verification tables to structure the process.
• Made file reading mandatory before a technology can be claimed.
• Implemented a sequential workflow where each step depends on the previous one.
• Increased the default reasoning effort to ensure higher quality analysis.

This change significantly improves the reliability of the Gadget service by grounding its
analysis in the actual content of the repository.

PLEASE TEST BEFORE MERGING!