docs(6207): the remaining migrations state their rationale in terms of the data

Record, milestone, phase and plan citations go from every migration header;
the "end before start" fix (0043) and the suppressed-count column (0095)
state the condition they prevent rather than the incident. 0053 and 0055
pointed at design specs under docs/superpowers that are not in the repo;
those pointers are removed.

Kept: alembic's generated "Create Date:" headers (template metadata, not
rationale), 0121's ARM_BORN justification beside the constant, and 0051's
illustrative "update task 42" format example.

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

alembic/versions/0106_rule_usage_events_carry_an_outcome.py

@@ -12,9 +12,7 @@ sessions leave identical telemetry:
   - a rule surfaced, opened, and silently ignored.
 
 The second is the more urgent by a distance, and it is the one the readout
-cannot name. That is the whole of what this milestone is about, measured on a
-session where three of seven misses were caught by the operator and none by
-the system.
+cannot name, and it is what an outcome column is for.
 
 TWO NEW EVENT VALUES, AND NO CHECK MIGRATION. `event` was created in 0094 as
 plain `sa.Text()` with no constraint — checked in the migration itself, not