docs(mcp): switch MCP transport stdio → SSE, update all references

MCP server is now a persistent SSE service on :8001 (make mcp-http),
independent of the Claude Code session. Re-registration is a single
claude mcp add-json command; no patch_mcp_cwd.py needed.

- Makefile: mcp-http is primary transport, add fuser restart + updated comment
- state-hub/README.md: stack table, MCP section, troubleshooting note updated
- CLAUDE.md (project): registration instructions rewritten for SSE

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

Makefile

@@ -25,11 +25,11 @@ migrate:
 seed:
 	uv run python scripts/seed.py
 
-## MCP server in SSE/HTTP mode for remote Claude Code sessions (e.g. COULOMBCORE).
-## Exposes the same tools as the stdio server over HTTP at http://127.0.0.1:8001/sse
-## Remote clients connect via the ops-bridge tunnel (port 18001 on the remote host).
-## Registration on the remote: claude mcp add-json -s user state-hub '{"type":"sse","url":"http://127.0.0.1:18001/sse"}'
+## Start (or restart) the MCP SSE server on :8001 — primary transport for Claude Code.
+## Remote clients (e.g. COULOMBCORE) connect via the ops-bridge tunnel (port 18001).
+## Registration: claude mcp add-json -s user state-hub '{"type":"sse","url":"http://127.0.0.1:8001/sse"}'
 mcp-http:
+	@fuser -k 8001/tcp 2>/dev/null && echo "Stopped running MCP server" || true
 	MCP_TRANSPORT=sse MCP_PORT=8001 uv run python mcp_server/server.py
 
 dashboard: