prompt: use {{.Tools}} for dynamic tool injection; update core submodule ref

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

core

@@ -1 +1 @@
-Subproject commit a81826b9090698cf18f4f6bddbb3fcf60582fc54
+Subproject commit e5e94e57fe36bde189613689dd0ac8bf4b646e20

prompts/SYSTEM_PROMPT.md

@@ -47,17 +47,10 @@ Supported languages are detected from the script's shebang line:
 - `#!/usr/bin/env bash` — runs with `bash -c`
 - `#!/usr/bin/env python3` — runs with `python3 -c`; `sys.argv` is set automatically when args are provided
 
-Unlike built-in tools, shell tools have no injected schema. Before using an unfamiliar tool, discover available tools and their usage:
+Unlike built-in tools, shell tools have no injected schema. Available tools and their usage:
 
-```
-execute_tool {tool: "tools"}                  # list all tools with descriptions and args
-```
-
-Each tool's header also documents itself directly:
-```
-# description: <what it does>
-# Args: <arg1> [arg2] ...
-```
+{{.Tools}}
+Each tool's header documents its full usage (`# description:`, `# Args:`).
 
 # Skills