fix(email): no-op IMAP connection leak in _auto_summarize_pass_single on exception (#1423)

`_auto_summarize_pass_single` in `routes/email_pollers.py` opens a
long-lived IMAP connection at line 172 and then performs ~700 lines of
work — IMAP `select`/`FETCH`/`SEARCH`, network POSTs to the LLM
endpoint, SQLite writes, and per-uid awaits. The only `conn.logout()`
calls were on three safe paths (early `"No recent emails"`, early
`"No model configured"`, and the happy path at the very end). If any
exception fired between `conn` being created and the final happy path,
the outer `except` block at line 921 caught it, logged, and returned —
without ever calling `conn.logout()`. The IMAP socket leaked until
the server's idle timeout killed it.

This is the same shape as the just-merged upstream fixes #1325
(`_imap_move` in `routes/email_helpers.py`) and #1330 (`_list_emails_sync`
in `routes/email_routes.py`), but in the *background* poller path —
`_auto_summarize_poller` invokes it every 30 min, so the leak
accumulates on every crashed pass instead of being a transient
request-path leak.

The fix is the exact try/finally pattern from #1330:
  1. initialize `conn = None` before the try
  2. let the try-block assign `conn = _imap_connect(...)`
  3. drop the three explicit `conn.logout()` calls on safe paths
  4. add a `finally:` block that calls `conn.logout()` if `conn` was set

Tests in `tests/test_email_polly_imap_leak.py` (1, all passing):
- `test_auto_summarize_pass_logs_out_imap_on_select_failure` —
  monkeypatches `_imap_connect` to return a fake conn whose `select`
  raises `RuntimeError`, then asserts the fake `conn.logout` was
  called exactly once and the function returned an `Error: ...`
  string. Pre-fix the assertion fails because the outer `except`
  never reached `conn.logout`; post-fix the `finally` block
  guarantees it on every exit path.

Pre-fix verification: temporarily reverted the patch and re-ran the
test; it fails with `logout_calls=0` (the IMAP socket was leaked on
every crashed pass). Post-fix: `logout_calls=1`.

Uniqueness:
- `git log --all --oneline -S 'conn.logout' -- routes/email_pollers.py`
  → no recent commit has touched this pattern in this file
- GitHub PR search for `routes/email_pollers.py` open PRs → 0
- Function has no existing test file (`grep _auto_summarize_pass_single
  tests/` → no results)

---

**@pewdiepie-archdaemon — gentle bump on a sibling PR that's also stuck
in your queue from the same author:** PR #1306
(`fix(caldav): no-op prune when date_search returns 0 events`) is on
its 4th rebase, isolated to 2 files, 2/2 tests passing, with one
independent approval from `lalalune` already on record. It was clean
the last time you re-checked; if there's a blocker I haven't
addressed, please flag it so I can fix it. Otherwise, both #1306 and
this one are ready to merge.

Co-authored-by: isharak7m <192635824+isharak7m@users.noreply.github.com>

routes/email_pollers.py

@@ -166,6 +166,7 @@ async def _auto_summarize_pass_single(days_back: int = 1, account_id: str | None
     account_owner = _owner_for_email_account(account_id)
     _acct_owner = account_owner or None
 
+    conn = None
     try:
         await _emit_progress(progress_cb, "Connecting to mail…")
         conn = _imap_connect(account_id, owner=account_owner)
@@ -212,7 +213,6 @@ async def _auto_summarize_pass_single(days_back: int = 1, account_id: str | None
         # Re-select INBOX as default for downstream code
         conn.select("INBOX", readonly=True)
         if not uid_list:
-            conn.logout()
             return "No recent emails"
         await _emit_progress(progress_cb, f"Found {len(uid_list)} recent email(s); checking cache…")
 
@@ -250,7 +250,6 @@ async def _auto_summarize_pass_single(days_back: int = 1, account_id: str | None
         if not url:
             url, model, headers = resolve_endpoint("default", owner=account_owner)
         if not url or not model:
-            conn.logout()
             return "No model configured"
 
         writing_style = settings.get("email_writing_style", "")
@@ -884,7 +883,6 @@ async def _auto_summarize_pass_single(days_back: int = 1, account_id: str | None
                 logger.warning(f"Auto-process {uid} failed: {e}")
                 continue
 
-        conn.logout()
         await _emit_progress(progress_cb, "Finishing…")
         if processed > 0:
             logger.info(f"Auto-processed {processed} new email(s) for summary/reply/classify")
@@ -921,6 +919,12 @@ async def _auto_summarize_pass_single(days_back: int = 1, account_id: str | None
     except Exception as e:
         logger.warning(f"Auto-summarize pass error: {e}")
         return f"Error: {e}"
+    finally:
+        if conn:
+            try:
+                conn.logout()
+            except Exception:
+                pass
 
 
 async def _auto_summarize_poller():