add AGENTS.md for LLM agents interfacing with this repository

[grokspawn]

Generated-by: Claude

prompt strategy:

Generate an AGENTS.md file for this repo. Ensure that AGENTS.md includes information about serving catalogsource content via opm serve and the gRPC interface thereof. Plus include information about the caching types for opm serve.
Ensure that AGENTS.md includes information that interfaces and approaches which interact with SQLite catalogs are deprecated, including a "(deprecated)" or similar notice for specifically enumerated commands and operations.
Ensure it is clear that any generated catalog image built by a dockerfile must be built and published to an image registry before it can be consumed. Also, make sure it is clear that opm render requires that FBC refer only to content already published to an image registry (for e.g. bundle images must be published before they can be referenced in a catalog). Lastly, ensure there is some discussion about migrating from SQLite to FBC by using either opm migrate or opm render, sometimes combined with opm alpha convert-template basic <filename>.

Then adjusted to add a couple of missing 'deprecation' indicators, remove an hallucinated parameter to opm migrate, and voila!

Description of the change:

Motivation for the change:

Reviewer Checklist

• Implementation matches the proposed design, or proposal is updated to match implementation
• Sufficient unit test coverage
• Sufficient end-to-end test coverage
• Docs updated or added to /docs
• Commit messages sensible and descriptive

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 55.37%. Comparing base (24737fb) to head (ba6dedb).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1817   +/-   ##
=======================================
  Coverage   55.37%   55.37%           
=======================================
  Files         136      136           
  Lines       16003    16003           
=======================================
  Hits         8861     8861           
  Misses       5987     5987           
  Partials     1155     1155           

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[openshift-ci]

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