Fix ssh-signing.md allowed_signers Snippet to Match host-setup.md - #974

PR #975 (the develop -> main promotion PR) surfaced this against #974's
change: the
"signing failed: no allowed signers" troubleshooting line paraphrased
the setup
snippet as an unquoted, truncated `echo ... >> ...` form. Copied
literally, a shell
strips the quotes around `"git"` (writing `namespaces=git` instead of
`namespaces="git"`), and the truncated destination path isn't a real
command.

Both CodeRabbit and Qodo flagged this independently on PR #975. Fix: use
the exact,
complete command from the setup section (matching line 35) instead of
paraphrasing it.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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## Summary by CodeRabbit

- **Documentation**
- Corrected the SSH signing troubleshooting command to use proper
quoting and the complete allowed signers file path.

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Promotes develop to main.

Includes:
- #974: Fix ssh-signing.md allowed_signers snippet to match
host-setup.md (fixes #713)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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-->
## Summary by CodeRabbit

* **Documentation**
* Updated SSH signing setup and troubleshooting instructions to use the
email address configured globally in Git.
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Promotes #981 (issue #947) to `main`.

## What

- `merge-and-release/SKILL.md` step 7's clean-tree preflight now scopes
its
  `git status --porcelain --untracked-files=all --ignored` check to
`-- .agents/skills/ .claude-plugin/` (all three carried copies), instead
of
  the whole checkout, matching `skills_install.py`'s own `source_ref()`
watched-path list. An ordinary build cache or lockfile elsewhere in the
  tree no longer blocks the refresh.
- `skills_install.py`'s install summary prints two separate lines, one
per
install target's own outcome, instead of folding both into one sentence.

## Review

PR #981 went through two review rounds:

- qodo flagged the PR title's lowercase "to" as a title-case violation.
Declined: `to` is an allowed lowercase title-case bind word per the
fleet's
  own convention, and this exact false positive is already documented in
  `docs/pr-reviewer-evaluation.md`.
- CodeRabbit correctly caught that the first pass under-scoped the
preflight
  to `.agents/skills/` alone, missing `.claude-plugin/`, which
`skills_install.py` also reads (`claude plugin marketplace add` installs
from it). Fixed, and CodeRabbit's re-review on the fixed head came back
  clean ("No actionable comments were generated in the recent review.").

Copilot's review account is still quota-exhausted repo-wide (confirmed
again
this session, consistent with recent PRs #974-980), so PR #981 merged to
`develop` on qodo + CodeRabbit coverage alone, both clean on the final
head,
CI green (8/8), `mergeStateStatus: CLEAN`.

Closes #947


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## Summary by CodeRabbit

* **Bug Fixes**
* Refined Skills refresh checks to include tracked, untracked, and
ignored files in all relevant installation paths.
  * Unrelated ignored files no longer block Skills refreshes.

* **Improvements**
* Installation results now separately report global Skills setup and
marketplace registration for clearer status visibility.

* **Documentation**
* Updated Skills refresh guidance to clarify which installation paths
are checked and how ignored files are handled.
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