fix(release): scope fallback to project history for new packages

[zanlucathiago]

Current Behavior

Closes #35327

When a project has no release tags (e.g., newly added to a monorepo), nx release falls back to getFirstGitCommit() — the very first commit in the entire repository. This means git log <first-commit>..HEAD scans every commit ever made, regardless of whether they are relevant to the new project.

In large monorepos this causes:

1. Severe performance degradation — the release step can take 5+ minutes just scanning irrelevant history
2. Noisy warnings — "The affected projects might have not been identified properly. The package(s) X were not found" for every old/renamed/removed package referenced in ancient commits
3. CI timeouts — the cumulative overhead can push pipelines past their timeout limits

Reproduction

1. Create a monorepo with release.changelog.automaticFromRef: true and release.version.conventionalCommits: true
2. Have a long git history (1000+ commits) with commits referencing packages that no longer exist
3. Add a new package to the workspace
4. Run nx release --skip-publish
5. Observe it scanning the entire git history and logging warnings for every unresolvable package reference

Expected Behavior

For new packages without release tags, nx release should only scan commits since the project was first introduced — not the entire repository history.

Implementation

Adds getFirstProjectCommit(projectRoot) in utils/git.ts:

git rev-list --reverse HEAD --first-parent -- <projectRoot>/package.json

This finds the first commit that touched the project's package.json and returns its parent, so that from..HEAD ranges include the creation commit itself.

The function is used as the fallback in two places:

Location	Before	After
deriveSpecifierFromConventionalCommits	getFirstGitCommit()	getFirstProjectCommit(projectRoot)
resolveChangelogFromSHA	getFirstGitCommit()	getFirstProjectCommit(projectRoot) when projectRoot is provided

For workspace-level and fixed release group changelogs (where there's no single project root), the existing getFirstGitCommit() behavior is preserved.

Fallback safety

If getFirstProjectCommit fails for any reason (e.g., the project root doesn't contain a package.json, or the git command fails), it gracefully falls back to getFirstGitCommit() — maintaining backward compatibility.

Impact

For a real-world monorepo with ~1200 commits and 4 new packages:

Metric	Before	After
Commits scanned per new package	~1200	Only commits since package was added
"Package not found" warnings	~30 per run	0
Release step time	5+ minutes	Seconds

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