chore: Add changeset for system message override fix

Added changeset describing the fix for low-limit model support:
- System message override now used exclusively without additional context
- Reduces token usage from ~9,059 to ~30 tokens
- Enables support for models like groq/qwen/qwen3-32b (6K TPM)
- Includes verbose mode for debugging API requests

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Co-Authored-By: Claude <noreply@anthropic.com>

Author: konard

.changeset/fix-system-message-override.md

@@ -0,0 +1,7 @@
+---
+'@link-assistant/agent': patch
+---
+
+Fix system message override to use exclusively without additional context for low-limit models. When --system-message flag is provided, the system now returns only that message without adding environment info, custom instructions, or headers. This reduces token usage from ~9,059 to ~30 tokens, enabling support for models with low TPM limits like groq/qwen/qwen3-32b (6K TPM).
+
+Also adds --verbose mode to debug API requests with system prompt content and token estimates.