chore: sweep dead config — thefuck, aider, tmux/oh-my-posh leftovers, nvim starter cruft, dead ignore patterns

- thefuck: remove the empty home_config/thefuck dir left behind after 2026-06-26's
  'drop thefuck'. Its ~/.config link, the ~/homebase venv that held only thefuck and
  its deps, and the thefuck/fuck wrappers were removed from nh3-dev at the same time.
- aider: remove .aider.conf.yml and .aider.model.settings.yml. The only configured
  backend was an Ollama qwq-32b endpoint, and the last session was 2025-03-21.
  Repo-root aider session artifacts were deleted and the aider-chat uv tool was
  uninstalled on nh3-dev.
- stow ignores: delete .stow-global-ignore and home_config/.stow-local-ignore. Their
  patterns were tmux plugins (the tmux config is gone) and ~/-prefixed paths that
  stow never matches, so they only displaced stow's built-in defaults.
- nvim: drop kickstart's vimtutor TEST file and upstream .github templates/CI.
- .gitignore: drop dead patterns (.config/*, /.aider*). Ignore per-machine zellij
  layouts, and guard Claude Code credentials and settings.local.json.

Dangling ~/.tmux.conf, ~/.config/tmux and ~/.config/ohmyposh links were also removed on nh3-dev.

home_config/.stow-local-ignore

@@ -1 +0,0 @@
-./tmux/plugins/

home_config/nvim/.github/ISSUE_TEMPLATE/bug_report.md

@@ -1,28 +0,0 @@
----
-name: Bug report
-about: Create a report to help us improve
-title: ''
-labels: ''
-assignees: ''
-
----
-
-<!-- Any bug report not following this template will be immediately closed. Thanks -->
-
-## Describe the bug
-<!-- A clear and concise description of what the bug is. -->
-
-## To Reproduce
-<!-- Steps to reproduce the behavior. -->
-1. ...
-
-## Desktop
-<!-- please complete the following information. -->
-- OS: 
-- Terminal: 
-
-## Neovim Version
-<!-- Output of running `:version` from inside of neovim. -->
-
-```
-```

home_config/nvim/.github/pull_request_template.md

@@ -1,8 +0,0 @@
-***************************************************************************
-**NOTE**
-Please verify that the `base repository` above has the intended destination!
-Github by default opens Pull Requests against the parent of a forked repository.
-If this is your personal fork and you didn't intend to open a PR for contribution
-to the original project then adjust the `base repository` accordingly.
-**************************************************************************
-

home_config/nvim/.github/workflows/stylua.yml

@@ -1,21 +0,0 @@
-# Check Lua Formatting
-name: Check Lua Formatting
-on: pull_request_target
-
-jobs:
-  stylua-check:
-    if: github.repository == 'nvim-lua/kickstart.nvim'
-    name: Stylua Check
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout Code
-        uses: actions/checkout@v2
-        with:
-          ref: ${{ github.event.pull_request.head.sha }}
-      - name: Stylua Check
-        uses: JohnnyMorganz/stylua-action@v3
-        with:
-          token: ${{ secrets.GITHUB_TOKEN }}
-          version: latest
-          args: --check .
-

home_config/nvim/TEST

@@ -1,21 +0,0 @@
- 1. Move the cursor to this line.
-
- 2. Press [v](v) and move the cursor to the fifth item below. Notice that the
-    text is highlighted.
-
- 3. Press the `:`{normal} character. At the bottom of the screen
-
-        `:'<,'>`{vim}
-
-    will appear.
-
- 4. Type
-
-        `w TEST`{vim}
-
-    where TEST is a filename that does not exist yet. Verify that you see
-
-        `:'<,'>w TEST`{vim}
-
-    before you press `<Enter>`{normal}.
-