[Performance] Memoize hasGit check

[gonzaloriestra]

WHY are these changes introduced?

Checking for Git presence via git --version is an expensive operation that involves spawning a new process. This check is performed multiple times during the execution of various CLI commands. Since Git's presence is unlikely to change during the execution of a single command, we can memoize the result to improve performance.

WHAT is this pull request doing?

This PR memoizes the hasGit function in packages/cli-kit/src/public/node/context/local.ts using a module-level promise.

• Introduced hasGitPromise to cache the result.
• Updated hasGit to return the cached promise if available.
• Added and exported _resetHasGit for test isolation.
• Updated unit tests in packages/cli-kit/src/public/node/context/local.test.ts to verify memoization.

How to test your changes?

CI

Post-release steps

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes
• I've considered analytics changes to measure impact
• The change is user-facing — I've identified the correct bump type (patch for bug fixes · minor for new features · major for breaking changes) and added a changeset with pnpm changeset add

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PR created automatically by Jules for task 1744815129505296381 started by @gonzaloriestra

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[github-actions]

Differences in type declarations

We detected differences in the type declarations generated by Typescript for this branch compared to the baseline ('main' branch). Please, review them to ensure they are backward-compatible. Here are some important things to keep in mind:

• Some seemingly private modules might be re-exported through public modules.
• If the branch is behind main you might see odd diffs, rebase main into this branch.

New type declarations

We found no new type declarations in this PR

Existing type declarations

packages/cli-kit/dist/public/node/context/local.d.ts

@@ -132,6 +132,11 @@ export declare function cloudEnvironment(env?: NodeJS.ProcessEnv): {
  * @returns A promise that resolves with the value.
  */
 export declare function hasGit(): Promise<boolean>;
+/**
+ * Resets the memoized value for the hasGit check.
+ * This is only intended for use in tests.
+ */
+export declare function _resetHasGit(): void;
 /**
  * Gets info on the CI platform the CLI is running on, if applicable.
  *