refactor: convert plugin tools to skills/ directory structure

Replace "tools" shell script declarations with proper skills/ directory
so Claude Code injects them into system-reminder and Skill tool can invoke them.

Each tool now has its own skills/<name>/SKILL.md with usage prompt.
Remove "type" and "tools" fields from plugin manifests.
Bump version to 1.0.3.

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

fission-python/.claude-plugin/plugin.json

@@ -2,7 +2,5 @@
   "id"         : "fission-python-skill",
   "name"       : "Fission-Python-Skill",
   "description": "Skill for creating, analyzing, and managing Fission Python projects.",
-  "type"       : "skill",
-  "tools"      : ["create-project", "analyze-config", "update-docstring"],
-  "version"    : "1.0.2"
+  "version"    : "1.0.3"
 }