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/skills/writing-plans/SKILL.md

@@ -85,8 +85,8 @@ step in the list, `{{ref:milestone}}` is the milestone. They are replaced with
 the real id and title as the records are created.
 
 **Do not** write plans or specs to local `.md` files — the milestone is the
-record, not a file on disk. (The old `kind=plan` task is retired; `start_planning`
-no longer creates one.)
+record, not a file on disk. A plan is never a task: `kind="plan"` is refused,
+and `start_planning` makes a milestone.
 
 Before designing from scratch, **recall**: `search` Scribe for a related prior
 decision or note. Often the thinking (or half of it) already exists.