fix(e2e): replace paths filter with content-hash cache skip

[roomote]

Related GitHub Issue

Description

Replaces the paths: trigger filter on the E2E workflow with a content-hash-keyed cache mechanism.

The old paths: filter caused the E2E required status check to be absent (not just skipped) on PRs that touched files outside the filter, which blocked merging. The new approach:

• Always runs the workflow so the required check is always present.
• On pull_request events, restores a pass-marker cache keyed on the hash of all relevant source files.
• Skips setup, install, and test steps when the cache hits (same source hash already passed).
• Writes and saves the pass marker after a successful run so future PRs with the same hash skip automatically.
• merge_group and workflow_dispatch events always run the full test suite regardless of cache state.

Also pins actions/cache/restore and actions/cache/save to their commit SHA (0057852) consistent with the rest of the repo's action pinning.

Test Procedure

• Reviewed the workflow diff locally.
• Cache key covers all source paths previously in the paths: filter, plus pnpm-workspace.yaml and the e2e workflow file itself.

Pre-Submission Checklist

• Issue Linked: This PR is linked to an approved GitHub Issue.
• Scope: Changes are focused on the e2e workflow caching fix.
• Self-Review: Performed a thorough self-review.
• Testing: CI-only change; validated by workflow logic review.
• Contribution Guidelines: I have read and agree to the Contributor Guidelines.

[roomote]

No actionable issues found. See task

• Cache key omits non-core workspace packages that feed the mocked E2E bundle, so this required check can skip on packages/types, packages/ipc, packages/cloud, or packages/telemetry changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[edelauna]

Adding this in since I'd like for e2e tests to be a required check, but it also doesn't make sense to run them on every PR.

[roomote]

I detected merge conflicts but could not start a task to address them.

[roomote]

This PR has merge conflicts that need to be resolved.

[roomote]

I detected merge conflicts but could not start a task to address them.

[roomote]

I detected merge conflicts but could not start a task to address them.

[roomote]

I detected merge conflicts but could not start a task to address them.

[roomote]

This PR has merge conflicts that need to be resolved.