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_precompact_preserve.sh

@@ -1,12 +1,7 @@
 #!/usr/bin/env bash
-# Scribe plugin — PreCompact: tell the summarizer what must survive (#3680).
+# Scribe plugin — PreCompact: tell the summarizer what must survive.
 #
-# WHAT THIS HOOK ACTUALLY DOES, and why it is not what the design first assumed.
-#
-# Spike #3680 asked whether a PreCompact hook can reach the model, and note
-# #3679 assumed the channel would be `hookSpecificOutput.additionalContext`
-# plus a block. Both halves of that are wrong, read out of the installed build
-# (Claude Code 2.1.273):
+# HOW A PRECOMPACT HOOK REACHES THE MODEL (as read out of Claude Code 2.1.273):
 #
 #   * `additionalContext` is NEVER read on PreCompact. The hook-output schema
 #     has no PreCompact variant at all; the field is honoured for SessionStart,
@@ -18,8 +13,8 @@
 #     operator typed after `/compact` and passed into the prompt that writes
 #     the summary. Every path does this — manual, auto and partial compaction.
 #
-# So there IS a model-reaching channel, and it is better than the one designed:
-# we do not interrupt the compaction, we steer the summary it produces. The
+# So the channel is the summary itself: we do not interrupt the compaction, we
+# steer the summary it produces. The
 # summary is what the next turn reads, so text that survives into it survives
 # the compaction.
 #
@@ -27,8 +22,7 @@
 # `{"decision":"block"}`) does not pause for the model and cannot tell it
 # anything — the compaction is SKIPPED, a warning goes to the operator's
 # screen, and the session continues uncompacted toward its context limit with
-# no summary at all. That failure is silent from the model's side, which is
-# exactly the outcome #3680 existed to avoid shipping. This hook exits 0 on
+# no summary at all, silently from the model's side. This hook exits 0 on
 # every path.
 #
 # SCOPE: in a subagent the handler discards hook stdout and keeps only a block,
@@ -49,11 +43,9 @@ set -uo pipefail
 # shellcheck source=plugin/hooks/scribe_defs.sh
 . "$(dirname "${BASH_SOURCE[0]}")/scribe_defs.sh"
 
-# THE EVENT IS NOW READ, where it used to be drained. The old comment here said
-# nothing in it changes what we emit, and that was true while every line was
-# static. It stopped being true at #4216: the slippage readout below is
-# specific to THIS session, and `session_id` is the key to the ledgers that
-# hold it. The instruction is still the same whether the operator typed
+# THE EVENT IS READ for `session_id`: the slippage readout below is specific
+# to THIS session, and the id is the key to the ledgers that hold it. The
+# instruction is still the same whether the operator typed
 # `/compact` or the session hit its limit — what varies is the measurement
 # appended to it.
 event=$(cat 2>/dev/null || true)
@@ -83,7 +75,7 @@ Everything else here can be recovered from the repository or from Scribe. These
 cannot: they are this session's only copy.
 EOF
 
-# ── The slippage readout (#4216, milestone 419) ───────────────────────────
+# ── The slippage readout ─────────────────────────────────────────────────
 #
 # WHY IT BELONGS HERE RATHER THAN IN A REPLY. A rule read and left unresolved
 # is invisible by construction: it looks exactly like a rule that worked. The