Drop stale internal markers from cluster/exceptions/pool comments

Three comments cited internal review markers (cycle numbers, retired
issue numbers) as cross-references. The markers go stale instantly —
cycle counters are internal review concepts and issue numbers get
reused after triage moves files. Replace each with the engineering
rationale itself ("symmetric with the pid guards", "verbatim server
text contract", "the prior _size accounting fix").

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: antoineleclair

src/dqliteclient/cluster.py

@@ -170,7 +170,7 @@ def __init__(
         # would observe an inherited task and ``await
         # asyncio.shield(<parent-loop task>)`` — undefined behaviour.
         # Symmetric with the DqliteConnection / ConnectionPool
-        # pid guards added in cycle 20.
+        # pid guards.
         self._creator_pid = os.getpid()
 
     @classmethod

src/dqliteclient/exceptions.py

@@ -101,10 +101,10 @@ def __init__(
         # un-suffixed). Callers compose the display ``message`` with
         # peer-address suffix / "Failed to connect:" prefix etc. and
         # pass the unadorned server text as ``raw_message=`` so the
-        # cycle-21 "raw_message is the bytes the server actually sent"
-        # contract is preserved through the dbapi-layer plumbing. Old
-        # call sites that omit the kwarg still get the previous
-        # behaviour (``raw_message`` defaults to ``message``).
+        # contract that raw_message is the verbatim server text is
+        # preserved through the dbapi-layer plumbing. Old call sites
+        # that omit the kwarg still get the previous behaviour
+        # (``raw_message`` defaults to ``message``).
         self.raw_message = message if raw_message is None else raw_message
         if len(message) > self._MAX_DISPLAY_MESSAGE:
             # ``len(message)`` and the slice cap count Python codepoints,

src/dqliteclient/pool.py

@@ -385,10 +385,10 @@ async def initialize(self) -> None:
                 # orphaned (transports leaked until GC).
                 #
                 # This is the symmetric resource-discipline fix to
-                # the ``_size`` accounting fix (ISSUE-240) — that fix
-                # moved the bookkeeping into the finally; the
-                # connection-close sweep now does the same by
-                # walking the explicit task list.
+                # the prior ``_size`` accounting fix that moved the
+                # bookkeeping into the finally; the connection-close
+                # sweep now does the same by walking the explicit
+                # task list.
                 create_tasks: list[asyncio.Task[DqliteConnection]] = [
                     asyncio.create_task(self._create_connection()) for _ in range(self._min_size)
                 ]