docs: rename GEMINI.md to AGENTS.md with updated guidelines

[cowsking]

• Filename Standard: Renamed GEMINI.md to AGENTS.md (the standard name auto-discovered by most agent harnesses).
• Repository Layout: Added a tabular map of the codebase so agents can locate components quickly without expensive directory traversals.
• Progressive Disclosure: Streamlined the build/test commands to keep the file concise, pointing agents to docs/development.md and docs/testing.md as the sources of truth instead of duplicating setup details.
• Skills Reference: Added a pointer to the .agents/ directory for any future repository-specific agent skills or automations.

[google-oss-prow]

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[gemini-code-assist]

Code Review

This pull request replaces the Config Sync GEMINI.md file with a new AGENTS.md file, which provides structured guidance for AI coding agents. The new documentation includes a project summary, repository layout, and build/test instructions. Review feedback suggests clarifying the scope of the make test command to include linting and kustomization, adding the make fmt-go command for code style compliance, and ensuring the file ends with a trailing newline for Unix compatibility.

[gemini-code-assist]

The description for make test has been updated to accurately reflect that it includes linting and kustomization tests as defined in the Makefile (line 394). Additionally, make fmt-go is included in the list as it is a critical step for ensuring code style compliance before submission.

Suggested change

	- `make test` — Runs fast Go unit tests.
	- `make test-e2e-kind` — Runs end-to-end validation against a local kind cluster (requires pre-installing kind via `make install-kind`).
	- `make test` — Runs unit tests, kustomization tests, and linting.
	- `make test-e2e-kind` — Runs end-to-end validation against a local kind cluster (requires pre-installing kind via `make install-kind`).
	- `make fmt-go` — Formats Go code using gofmt and goimports.

[gemini-code-assist]

The file is missing a newline at the end. It is a standard practice to end text files with a newline to ensure compatibility with various Unix tools and to avoid issues with diffs.

Suggested change

	Shared agent skills and custom automations for working in this repository should be organized within an `.agents/` directory following emerging repository standards.
	Shared agent skills and custom automations for working in this repository should be organized within an .agents/ directory following emerging repository standards.

[tiffanny29631]

Not seeing the dependency bump rules described, I guess the agent is only counting in the build/test rules for now, not our customized maintenance logics. Is it now an option to deploy agents in the repo and help us bump the deps like Helm? It would be super nice to see a sample of that.