ci(godot): consolidate toolchain steps into the load-godot-toolchain action

[itsmiso-ai]

Refactored Godot toolchain loading into a composite action to centralize setup logic for CI workflows.

Fixes #347

Opened by foreman on review GO (workload wl-misospace-windowstead-347).

[its-saffron]

AI Automated Review

Full PR review.

Analysis engine: MiniMax-M2.7@https://litellm.jory.dev/v1 (anthropic) — primary route

Recommendation: Approve

This PR cleanly addresses issue PR 347 by transforming the load-godot-toolchain composite action from a config-only resolver into a full toolchain loader that handles download, verification, dependency installation, template installation, smoke testing, and test suite execution.

Change-by-Change Findings

.github/actions/load-godot-toolchain/action.yml

• The action grows from ~54 lines (config-only) to ~221 lines, now embedding all the previously copy-pasted logic for: download/unzip/chmod, system dependency installation (libfontconfig1), export template installation, and both Linux and macOS smoke test wrappers
• Four new boolean inputs (platform, install_templates, run_smoke, run_tests) gate platform-specific and step-specific behavior via if: conditions
• A new output godot_binary is produced by the install step and propagated to downstream steps, replacing the need for jobs to reconstruct the binary path from version/status outputs
• The config-reading Python script is reformatted with a resolve() helper and explicit GITHUB_OUTPUT file writes (matching the prior behavior, just cleaner)
• Platform branching (linux vs macos) is correctly separated for download, template dir paths, and smoke test invocation

.github/workflows/test.yml

• All seven jobs (smoke-test, script-tests, macos-validation, export-validation, export-validation-windows, export-validation-macos, export-validation-web) are reduced to a single uses: ./.github/actions/load-godot-toolchain call with appropriate inputs, plus platform-specific export steps
• The entire "Download Godot" block (download, unzip, chmod, verify) is gone from every job — satisfied by the action
• The "Install Godot system dependencies" block is gone from smoke-test, script-tests, and all export jobs — gated inside the action for Linux only
• The "Run headless smoke test" block is gone from smoke-test and macos-validation — driven by run_smoke: "true"
• The "Run all test suites" block is gone from script-tests and macos-validation — driven by run_tests: "true"
• Export jobs use ${{ steps.godot.outputs.godot_binary }} instead of reconstructing the path, which is cleaner and matches the action's new output

Linked Issue Fit

Issue PR 347 acceptance criteria are met:

Criterion	Status
Single composite action performs download, checksum, install, test-suite loop	✓ — action now embeds all four
Each job invokes with minimal platform-specific inputs	✓ — jobs pass platform, run_smoke, run_tests, install_templates
test.yml has no more than one copy of the run-all-tests suite loop	✓ — removed from script-tests and macos-validation
test.yml has no more than one copy of the Linux download/install steps	✓ — removed from smoke-test, script-tests, and all export jobs
All five validation jobs still pass	✓ — confirmed by CI results

Standards Compliance

Per AGENTS.md, this repository uses push-to-main for CI-only changes. No release process applies. The diff is confined to .github/ files and requires no GDScript or game-code validation.