feat: add development and hf-hangman-lab skills

development: absorbed openclaw-plugin-dev as a workflow, with
reference docs for plugin structure, hooks, tools, state, config.

hf-hangman-lab: hf-wakeup workflow — full agent wakeup lifecycle:
set busy → check due slots → select & defer → identify task →
plan work → create work channel → execute. All branches end with
status reset to idle.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

development/SKILL.md

@@ -0,0 +1,12 @@
+---
+name: development
+description: Software development workflows — plugin development, code review, and implementation patterns. Use when building OpenClaw plugins, implementing features, or following development processes.
+---
+
+## Workflows
+
+- `{baseDir}/workflows/openclaw-plugin-development.md` — When creating or modifying OpenClaw plugins. Covers project structure, entry points, hooks, tools, state management, config, and debugging.
+
+## Reference
+
+- `{baseDir}/docs/` — Plugin development reference docs (structure, hooks, tools, state, config, debugging).