style(skills): clear the markdownlint findings that kept make test red

Eight findings, none of them in a skill written recently, all of them loud enough to hide the next real one. merge-fix opened two code fences without a language, and no-defaults wrote its table separator as |---|---|---| while all six data rows put spaces around the pipes, which markdownlint reads as a style contradiction and reports six times over for that single line.

Nothing about the rendered documents changes: the fence language only selects highlighting, and the separator row is not rendered at all. make test now passes end to end, so the next finding it reports will be a new one.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

skills/merge-fix/SKILL.md

@@ -20,7 +20,7 @@ same tree may own.
 
 ## 2. Fetch everything
 
-```
+```bash
 git fetch --all --prune --tags
 ```
 
@@ -37,7 +37,7 @@ one line so a wrong reading is visible before the search.
 
 Run all three; they find different things:
 
-```
+```bash
 git log --all --oneline --regexp-ignore-case --grep='<keyword>'
 git log --all --oneline -S'<symbol or literal>'
 git log --all --oneline -- '<path or glob>'

skills/no-defaults/SKILL.md

@@ -59,7 +59,7 @@ with `false`, `null`, or `""` is permitted, and with any other value is permitte
 only when justified in a comment.
 
 | Language | Never | Instead |
-|---|---|---|
+| --- | --- | --- |
 | Bash | `${VAR:-x}`, `${VAR:=x}`, `: "${VAR:=x}"` | `: "${VAR:?set VAR in <file>}"` |
 | Python | `def f(a=1)`, `d.get(k, x)`, `getattr(o, n, x)`, `os.environ.get(k, x)`, `argparse(default=)` | required args, `d[k]`, `os.environ[k]`, `add_argument(required=True)` |
 | Jinja / Ansible | `\| default(x)`, `lookup('env', k) \| default('')` | `\| mandatory`, `assert` on the var |