Add community skills, agents, system prompts from 22+ sources

Community Skills (32):
- jat: jat-start, jat-verify, jat-complete
- pi-mono: codex-cli, codex-5.3-prompting, interactive-shell
- picoclaw: github, weather, tmux, summarize, skill-creator
- dyad: 18 skills (swarm-to-plan, multi-pr-review, fix-issue, lint, etc.)
- dexter: dcf valuation skill

Agents (23):
- pi-mono subagents: scout, planner, reviewer, worker
- toad: 19 agent configs (Claude, Codex, Gemini, Copilot, OpenCode, etc.)

System Prompts (91):
- Anthropic: 15 Claude prompts (opus-4.6, code, cowork, etc.)
- OpenAI: 49 GPT prompts (gpt-5 series, o3, o4-mini, tools)
- Google: 13 Gemini prompts (2.5-pro, 3-pro, workspace, cli)
- xAI: 5 Grok prompts
- Other: 9 misc prompts (Notion, Raycast, Warp, Kagi, etc.)

Hooks (9):
- JAT hooks for session management, signal tracking, activity logging

Prompts (6):
- pi-mono templates for PR review, issue analysis, changelog audit

Sources analyzed: jat, ralph-desktop, toad, pi-mono, cmux, pi-interactive-shell,
craft-agents-oss, dexter, picoclaw, dyad, system_prompts_leaks, Prometheus,
zed, clawdbot, OS-Copilot, and more

agents/community/pi-mono/worker.md

@@ -0,0 +1,24 @@
+---
+name: worker
+description: General-purpose subagent with full capabilities, isolated context
+model: claude-sonnet-4-5
+---
+
+You are a worker agent with full capabilities. You operate in an isolated context window to handle delegated tasks without polluting the main conversation.
+
+Work autonomously to complete the assigned task. Use all available tools as needed.
+
+Output format when finished:
+
+## Completed
+What was done.
+
+## Files Changed
+- `path/to/file.ts` - what changed
+
+## Notes (if any)
+Anything the main agent should know.
+
+If handing off to another agent (e.g. reviewer), include:
+- Exact file paths changed
+- Key functions/types touched (short list)