docs(hacktober): mark 12 more resolved PRs in the 2026 tracker - #15196

Per @cclauss's request on #15081, refreshing the checkboxes in docs/hacktober_2026_prep.md. (Reopening #15195, which the keeper bot auto-closed because the template checklist below was missing — same diff, now with the checklist.)

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• Added doctests to game_of_life.py #12109 — game_of_life doctests, superseded by the merged Add doctests for Conway's Game of Life #13146 (which added doctests for create_canvas/run/__judge_point)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.

Describe your change:

Documentation-only refresh of the Hacktoberfest 2026 tracker checkboxes. No algorithm files touched.

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".