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_sync.py

@@ -101,7 +101,7 @@ def test_page_cursor_a_full_revocation_stream_holds_the_cursor_back():
     assert more is True
 
 
-# --- protocol handshake (M10.6) ---------------------------------------------
+# --- protocol handshake -----------------------------------------------------
 
 
 def test_protocol_advertisement_shape():