chore: restructure project layout and cleanup stale artifacts

- Removed empty directories: agent-deploy/, agent-market/, agent-protocol/
- Moved standalone HTML docs into docs/proposals/ (agent-builder-proposal, agent-builder-smart-plan, agent-hub-tech-doc)
- Consolidated agent definitions from self-bootstrap-demo/, test-agents/, wecom-assistant-package/ into agents/
- Moved scattered root files (wecom-assistant-*, COMPLETION_SUMMARY.txt, README_PROJECT.md) to downloads/ and docs/
- Deleted agent-bridge/ (orphaned package-lock.json) and agent-market-fe/ (deployed build artifact)
- Updated .gitignore to remove stale path references

Author: xiaopeng.lei

.gitignore

@@ -16,8 +16,6 @@ dist/
 dist-ssr
 build/
 *.local
-agent-deploy/node/dist/
-agent-deploy/python/dist/
 
 # Data
 data/
@@ -73,14 +71,3 @@ temp/
 
 # Patches
 *.patch
-
-# Embedded git repos (added as submodules or separate pushes)
-agent-builder/
-agent-market/
-
-# Market specific
-agent-market/data/
-agent-market/src/market/static/
-
-# Agent test files
-test-agents/*/