feat(sproutclaw): modularize webui, extensions, and agent config layout

Restructure local extensions into per-feature directories, split WebUI
into backend modules with slash commands and systemd support, and track
prompts/skills under .pi/agent for portable Gitea deployment.

Co-authored-by: Cursor <cursoragent@cursor.com>

.gitignore

@@ -41,15 +41,26 @@ plans/
 .pi/sessions/
 .pi/extensions/webui/.webui.pid
 .pi/extensions/webui/.webui.log
+# Local runtime / secrets (do not commit)
+.local/
+progress.md
+
 # Pi agent: track extensions, ignore local runtime secrets and sessions
 .pi/agent/sessions/
 .pi/agent/git/
 .pi/agent/npm/
+.pi/agent/bin/
 .pi/agent/auth.json
 .pi/agent/models.json
 .pi/agent/settings.json
+.pi/agent/mcp.json
 .pi/agent/mcp-cache.json
+.pi/agent/mcp-npx-cache.json
 .pi/agent/run-history.jsonl
+.pi/agent/taskplane/
+.pi/agent/skills-disabled/
+.pi/agent/skills/.Recycle_bin/
+.pi/agent/skills/.system/
 .pi/agent/extensions/webui/frontend/node_modules/
 .pi/agent/extensions/webui/.webui.pid
 .pi/agent/extensions/webui/data/