Rollback standalone embedded webhook listener #43
Description
purpose
Revert the embedded standalone webhook listener introduced in v0.4.0 and return github-webhook-mcp to the previous split model where webhook reception is handled separately from the MCP reader.
premise
- standalone embedded listening only works while the stdio MCP process is alive
- webhook delivery must not depend on the AI client currently running
- v0.4.0 added embedded listener/config/docs that need to be removed
constraints
- keep the Anthropic local directory submission improvements from v0.3.1
- remove standalone listener wiring from the Node MCP server and plugin config surface
- align docs/package metadata with the split receiver model again