Server comments describe the code to a stranger (#6221)

Rule 32 "Comments describe the product to a stranger" sweep over
src/, alembic/ and tests/. Comments and docstrings now say what the code
does and the reason as a present-tense constraint, briefly.

Removed:
- issue, task, note, rule, milestone and family-idea references
- "used to" / before-and-after narration
- quotes of decisions and incident stories from the deploying instance
- paragraph-length arguments, where a line or two carries the fact

Kept every hazard as a present-tense fact, e.g. timing oracles, the
proxy hop direction, and migrations that must stay frozen.

Also:
- Three test names lose "still"/"used to"/"pre_m304" phrasing.
- pyproject's description drops "FabledSword family".

The history these comments carried stays in Scribe and in git log.
A comment-stripping diff (Scribe snippet #6226 "codeonly.py — prove a
diff changed only comments") shows no code changed apart from the
renamed tests and the description string.

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

tests/test_retention.py

@@ -26,9 +26,8 @@ def test_zero_means_keep_forever():
 
 
 def test_a_negative_window_also_means_never():
-    # Reachable by typing a stray minus into the Settings field. The dangerous reading
-    # of -1 would be "expired a day in the FUTURE", which purges the entire trash on
-    # the next sweep; refusing to run is the only safe interpretation.
+    # A stray minus in Settings. Read as "expired a day in the future", -1 would purge
+    # the whole trash, so it means "never".
     assert expired_before(NOW, -1) is None
     assert expired_before(NOW, -3650) is None
 
@@ -45,7 +44,7 @@ def test_retention_setting_is_registered_with_a_30_day_default():
     assert defn is not None, "the setting must appear in the admin Settings UI"
     assert defn.type == "int"
     assert defn.default == 30
-    # The operator has to be able to tell what it does without reading the code.
+    # An admin can tell what it does without reading the code.
     assert "0" in defn.description, "the keep-forever escape hatch must be documented"