fix: check add commit message first for squash merge PR detection

[jxom]

Problem

For squash merges, the PR number is in the commit message itself (e.g., feat: something (#37)). The previous implementation checked for merge commits first, which found the wrong PR on release branches.

Solution

Reorder the detection logic:

1. First check the add commit's message for a PR number (handles squash merges)
2. Fall back to looking for merge commits (handles traditional merges)
3. Return no PR number if neither found

This ensures correct PR attribution for repositories using squash-and-merge workflow.

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Project	Deployment	Actions	Updated (UTC)
changelogs-rs	Ready	Preview, Comment	Feb 4, 2026 4:49am

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changelogs: patch
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Fixed PR number detection to check the add commit message first for squash merge cases before looking for merge commits.

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