Add AGENTS.md for LLM guidance on Spyglass standards and conventions

[Copilot]

This PR adds a comprehensive AGENTS.md file to provide Large Language Models (LLMs) and AI agents with essential guidance for working with the Spyglass neuroscience data analysis framework. The file serves as a definitive reference to ensure consistent and correct assistance when helping developers create new Spyglass tables, pipelines, and analyses.

What's included

The AGENTS.md file provides:

• Core Architecture Overview: DataJoint foundations, SpyglassMixin requirements, and schema organization patterns
• Detailed Table Type Definitions: Comprehensive coverage of Parameters, Selection, Computed, NWB Ingestion, and Merge tables with practical code examples
• Development Standards: Naming conventions, code organization principles, and required method implementations
• LLM-Specific Best Practices: Guidelines for creating tables, common workflows, and avoiding typical mistakes
• Validated Patterns: All examples verified against actual Spyglass codebase implementation

Key benefits

This documentation will help LLMs:

• Understand the mandatory SpyglassMixin inheritance pattern: class MyTable(SpyglassMixin, dj.TableType)
• Select appropriate table types based on use case (Lookup for parameters, Manual for selections, Computed for analysis)
• Follow established naming conventions and schema organization
• Implement required methods like make() and insert_default()
• Handle NWB file operations and DataJoint dependencies correctly

Example usage guidance

The file includes practical examples like this Parameters table pattern:

@schema
class MyAnalysisParameters(SpyglassMixin, dj.Lookup):
    definition = """
    analysis_params_name: varchar(32)
    ---
    analysis_params: blob
    """
    
    contents = [
        ["default", {"threshold": 0.5, "window_size": 100}],
    ]
    
    @classmethod
    def insert_default(cls):
        cls().insert(rows=cls.contents, skip_duplicates=True)

The documentation ensures LLMs will provide assistance that maintains consistency with Spyglass standards while helping developers create robust, reproducible neuroscience analysis pipelines.

Fixes #1406.

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[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 70.54%. Comparing base (be9314f) to head (e75209b). :warning: Report is 20 commits behind head on master.

Additional details and impacted files

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  Coverage   70.54%   70.54%           
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  Files         104      104           
  Lines       12650    12650           
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  Hits         8924     8924           
  Misses       3726     3726           

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[edeno]

Possibly should wait to merge until https://github.com/LorenFrankLab/spyglass/pull/1377 is merged