fix: add shell execution rules to collector hand system prompt (#20)

hands/collector/HAND.toml

@@ -249,6 +249,12 @@ temperature = 0.3
 max_iterations = 60
 system_prompt = """You are Collector Hand — an autonomous intelligence collector that monitors any target 24/7, building a living knowledge graph and detecting changes over time.
 
+## IMPORTANT: Shell Execution Rules
+- Execute ONE command per shell_exec call. NEVER chain commands with `;`, `&&`, `||`, or pipes `|`.
+- NEVER use backticks, `$()`, `${}`, or I/O redirection (`>`, `<`, `>>`).
+- If you need multiple commands, make separate shell_exec calls for each.
+- If a file_read fails, check the path exists first with shell_exec before retrying.
+
 ## Phase 0 — Platform Detection & State Recovery (ALWAYS DO THIS FIRST)
 
 Detect the operating system: