fix(repo): replace leftover circleci cache syntax with actions equiva…

[Patrycja-dz]

• Fixes the failing Windows harness job and its root cause: SHAs are no longer written to /tmp under pwsh (which resolved to D:\tmp\ and crashed) but passed through step outputs, with explicit
  $LASTEXITCODE/empty-string guards; commit.yml gains fetch-depth: 2 so HEAD~1 resolves in the otherwise depth-1 clone.
• Removes dead CircleCI templating from four composite actions. {{ checksum "..." }} and {{ arch }} are never interpolated by GitHub Actions, so every affected cache key had been a constant literal string;
  they now use hashFiles(), runner.os, runner.arch, and step outputs, with keys reordered to <os>-<node>-<sha> so restore-keys prefixes can pin OS and Node version.
• Repairs install-ldid: path: UPDATE_ME meant the cache never restored; the guard also now tests for the built binary (-x ldid/ldid) and clears a partial tree before rebuilding.

Does this PR introduce a breaking change?

• Yes
• No

[Copilot]

Pull request overview

Updates GitHub Actions workflows/composite actions to replace leftover CircleCI cache templating with proper GitHub Actions expressions and to fix test-harness caching on Windows by passing SHAs via step outputs (instead of writing to /tmp).

Changes:

• Ensure actions/checkout uses fetch-depth: 2 where HEAD~1 is needed for cache key derivation.
• Replace {{ checksum ... }} / {{ arch }} cache key literals with hashFiles(), runner.os, runner.arch, and step outputs.
• Fix install-ldid cache path and rebuild guard to properly restore/build/cache the expected binary.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
.github/workflows/commit.yml	Sets fetch-depth: 2 for Windows checkout to support HEAD~1-based cache keys.
.github/actions/test-harness-windows/action.yml	Computes SHAs via step outputs in pwsh and updates cache keys/restore prefixes accordingly.
.github/actions/test-harness-linux/action.yml	Computes SHAs via step outputs in bash and updates cache keys/restore prefixes accordingly.
.github/actions/install-ldid/action.yml	Fixes cache key semantics and corrects the cache path/rebuild guard for the ldid build tree.
.github/actions/cached-dependencies/action.yml	Replaces CircleCI templating in Yarn cache keys with runner.os/arch + hashFiles('yarn.lock').

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