docs(hacktober): mark 12 PRs resolved since the #15189 batch

[priya-sundaram-dev]

Per @cclauss's request on #15081, refreshing the checkboxes in docs/hacktober_2026_prep.md.

Since the #15189 batch, 12 more tracked PRs have been resolved. I verified each against the live PR state (gh api .../pulls/<n>):

Merged (9): #13146, #13149, #13827, #13896, #14728, #14979, #15156, #15158, #15180

Closed by a maintainer (3):

• Added doctests to game_of_life.py #12109 — game_of_life doctests, superseded by the merged Add doctests for Conway's Game of Life #13146 (which added doctests for create_canvas/run/__judge_point)
• fix(sorts): add testmod() call to gnome_sort __main__ block #15146 — closed by @cclauss
• Create blacklistipchecker.py #9416 — closed as a how-to-use rather than an algorithm (per CONTRIBUTING.md)

Each of the 12 is checked off in both the numbered list and the grouped-by-directory list, and I added a Latest refresh note under the snapshot header recording the split (9 merged / 3 closed) and that ~752 PRs remain open. The Closed totals table is unchanged since these were merges/manual closes rather than close_pull_requests_with_*.sh runs.

No tracked-open lines remain that point at an already-closed PR.

[algorithms-keeper]

Closing this pull request as invalid

@priya-sundaram-dev, this pull request is being closed as none of the checkboxes have been marked. It is important that you go through the checklist and mark the ones relevant to this pull request. Please read the Contributing guidelines.

If you're facing any problem on how to mark a checkbox, please read the following instructions:

• Read a point one at a time and think if it is relevant to the pull request or not.
• If it is, then mark it by putting a x between the square bracket like so: [x]

NOTE: Only [x] is supported so if you have put any other letter or symbol between the brackets, that will be marked as invalid. If that is the case then please open a new pull request with the appropriate changes.