docs(6204): shipped instruction text describes the product, not this instance's records

MCP tool docstrings and comments, the server's orientation notes, the plugin
skills, every hook script and the plugin README/PACKAGING drop record ids,
milestone numbers, dates and incident stories, and state each non-obvious why
as a present-tense fact. History stays in the task logs.

Corrections found on the way:
- plugin README/PACKAGING said every hook is a GET; moment, rule-opened and
  reply-rules POST, so the plugin's key needs write scope. Both now say so,
  name Settings -> MCP Access, and list every wired hook and endpoint.
- the contract-change hint printed "(lesson #4207)", this instance's record,
  to every install. It no longer cites a record.
- tasks.py claimed there is no delete_task; there is.
- rulebooks.py cited delete_event and a design spec that no longer exist.
- scribe_after_write.sh carried an always-empty etag_q; removed.
- test_write_path_trigger pinned "| tac | scribe_defs | head -1", text that
  existed only in a comment about the old code; it now pins the real tail -1
  pipeline.
- docs/development.md: CI runs on Gitea Actions.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

plugin/hooks/scribe_shape_check.sh

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 # Scribe plugin — Stop hook: the turn's new shapes are judged by the agent
-# that wrote them (milestone 439).
+# that wrote them.
 #
 # The write hooks (scribe_prior_art.sh, scribe_after_write.sh) append every
 # definition a write names to a session ledger, `<sid>.written.ids`