docs(6207): migrations 0088 and 0090-0094 state their rationale in terms of the data

Milestone/step labels, record ids, the rescoped-rule date and the 296-call
measurement go; each header states what the change protects. "rule 36"
citations become the DROP + ADD practice they named.

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

alembic/versions/0093_rule_versions.py

@@ -1,4 +1,4 @@
-"""rules gain an edit history — rule_versions (milestone 323 step 1)
+"""rules gain an edit history — rule_versions
 
 Revision ID: 0093
 Revises: 0092
@@ -7,12 +7,9 @@ Create Date: 2026-08-29
 The sibling `note_versions` has had for a long time. A note's every meaningful
 edit is snapshotted, and the design-system note calls that history "the
 changelog". A RULE — which binds behaviour on every session that loads it —
-had nothing: an edit destroyed what it used to say, with no record anywhere.
-
-Rescoping rule 79 on 2026-08-29 is what surfaced it. The superseded statement
-had to be hand-copied into a task log to survive the edit (#3237), which is
-not a process, it is a person remembering. The more consequential record had
-the weaker protection.
+had nothing: an edit destroyed what it used to say, with no record anywhere,
+and keeping a superseded statement meant a person remembering to copy it
+somewhere. The more consequential record had the weaker protection.
 
 Three things are deliberately NOT copied from note_versions, and each is a
 guard that exists there for a reason that does not hold here:
@@ -31,7 +28,7 @@ guard that exists there for a reason that does not hold here:
 CASCADE: deleting a user must not erase the history of the rules they edited.
 The edit still happened and the rule still binds because of it.
 
-No CHECK constraint, so rule 36 does not apply. Nothing is backfilled — a
+No CHECK constraint is involved. Nothing is backfilled — a
 migration cannot invent the text a rule used to have, and inventing "the
 current text, as of now" would be worse than an empty history, because it
 would look like a record of an edit that never occurred.