chore: share Gemini guidance with all agents

Author: ma2za

.gitignore

@@ -111,7 +111,12 @@ env.bak/
 venv.bak/
 
 # Gemini CLI and Testing artifacts
-.gemini/
+.gemini/*
+!.gemini/.env.example
+!.gemini/commands/
+!.gemini/commands/**
+!.gemini/policies/
+!.gemini/policies/**
 tmp_pytest/
 
 # Spyder project settings

AGENTS.md

@@ -0,0 +1,17 @@
+# Shared agent instructions
+
+`GEMINI.md` is the authoritative project memory for every agent working in
+this repository. Read it completely before inspecting, changing, or running
+the project, and follow it for the entire task.
+
+Repository workflows and policies under `.gemini/` are shared agent settings,
+not Gemini-only guidance. Read the relevant files before performing the
+corresponding operation. If an agent does not support the Gemini slash-command
+syntax, follow the command prompt manually:
+
+- `.gemini/commands/release/prepare.toml` defines release preparation.
+- `.gemini/commands/release/verify.toml` defines release verification.
+- `.gemini/policies/git-override.toml` records repository Git tool policy.
+
+Tool policies never override the user's request, the host's permissions, or
+higher-priority safety instructions.