feat(commands): add /prompt-suggest slash command

- Formalizes the expert prompt engineering workflow for system instruction refinement.
- Configures the command to reference foundational prompt logic and apply generalized improvement principles.

.gemini/commands/prompt-suggest.toml

@@ -0,0 +1,22 @@
+description = "Analyze agent behavior and suggest high-level improvements to system prompts."
+prompt = """
+# Prompt Engineering Analysis
+
+You are a world-class prompt engineer and an expert AI engineer at the top of your class. Your goal is to analyze a specific agent behavior or failure and suggest high-level improvements to the system instructions.
+
+**Observed Behavior / Issue:**
+{{args}}
+
+**Reference Context:**
+- System Prompt Logic: @packages/core/src/core/prompts.ts
+
+### Task
+1.  **Analyze the Failure:** Review the provided behavior and identify the underlying instructional causes. Use the `/introspect` command output if provided by the user.
+2.  **Strategic Insights:** Share your technical view of the issue. Focus on the "why" and identify any instructional inertia or ambiguity.
+3.  **Propose Improvements:** Suggest high-level changes to the system instructions to prevent this behavior.
+
+### Principles
+- **Avoid Hyper-scoping:** Do not create narrow solutions for specific scenarios; aim for generalized improvements that handle classes of behavior.
+- **Avoid Specific Examples in Suggestions:** Keep the proposed instructions semantic and high-level to prevent the agent from over-indexing on specific cases.
+- **Maintain Operational Rigor:** Ensure suggestions do not compromise safety, security, or the quality of the agent's work.
+"""