feat: Update publish issue body when re-running GitHub Action

[BYK]

Summary

• Updates existing publish request issue instead of skipping when re-running the GitHub Action
• Preserves checked state of targets (already-published or user-skipped) when updating
• Refreshes all other content: requester, merge target, links, changelog, and target list

Motivation

When running the release action multiple times for the same version (e.g., after fixing CI issues or updating changelog), the publish request issue would remain stale. Now the issue body reflects the latest state while preserving user decisions about which targets to skip.

Behavior

Scenario	Before	After
Re-run with same targets	Skip, stale body	Update body, preserve checked states
Re-run with new targets	Skip, missing targets	Update body, new targets unchecked
Re-run with removed targets	Skip, invalid targets	Update body, removed targets gone
First run	Create issue	Create issue (unchanged)

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[BYK]

Re: Regex captures only first word of target names

This is a false positive. Target IDs are single-word identifiers by design - they're generated in src/targets/base.ts:29-33 as either {name} (e.g., github, npm, pypi) or {name}[{id}] (e.g., npm[registry], crates[custom-id]). They never contain spaces, so \S+ correctly captures the entire target name.

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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