feat: consolidate marketplace skills into kyberforge plugin

Moves create-plugin, marketplace-architect, write-skill, and write-eval
from canonical .agents/skills/ into plugins/kyberforge/skills/, along
with all bundled sub-files, evals, and the plugin-marketplace-architecture
research doc. Bundles templates/plugin/ into create-plugin/assets/plugin-template/
so the skill is self-contained after install-time caching. Removes
templates/plugin/ and docs/research/plugin-marketplace-architecture.md
from the repo root as they are now exclusively in the plugin.

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

plugins/kyberforge/skills/create-plugin/assets/plugin-template/bin/README.md

@@ -0,0 +1,11 @@
+# bin/
+
+**Claude Code only.** Executables placed here are added to PATH when the plugin is installed.
+
+Use this for CLI tools, helper scripts, or MCP server entry points bundled with the plugin.
+
+Reference files in this directory from `.mcp.json` or hooks using `${CLAUDE_PLUGIN_ROOT}/bin/<file>`.
+The `${CLAUDE_PLUGIN_ROOT}` variable resolves to the plugin's install cache path at runtime —
+do not use relative paths from the repo root, as they will break after install.
+
+GitHub Copilot CLI does not support `bin/`. If you add executables here, they are Claude Code only.