Extract the shared runner-setup pipeline

[bendrucker]

Extracts the load→annotate→vars→build→runners pipeline into a single tflint.BuildRunners function and routes both callers through it. The same sequence (LoadRootModule → LoadConfigDirFiles → NewAnnotations → LoadValuesFiles → ParseVariableValues → BuildConfig → NewRunner → NewModuleRunners) had emerged twice, near-verbatim, in cmd/inspect.go (setupRunners) and langserver/handler.go (inspect).

Scope is limited to runner setup. The plugin config-apply loop, ruleset.Check, the autofix loop, parallelism, and diagnostics stay in their callers because they differ in real ways (version-constraint checks, the Fix flag, parallel module runners, plugin lifecycle, LSP diagnostic conversion). Unifying those is out of scope and would force a different package home to avoid a tflint → plugin → tflint import cycle.

Changes

• Adds tflint.BuildRunners(loader, config, workingDir, dir) in the new tflint/runner_set.go, lifted from cmd's setupRunners body.
• Routes cmd/inspect.go and langserver/handler.go through it; deletes setupRunners and the langserver inline block.
• Keeps terraform.NewLoader construction in the callers. cmd needs the loader before setup for the worker-mode IsConfigDir check and after for Files()/Sources(); langserver builds it from its in-memory afero.Fs overlay and reuses it for Files() in the Check loop. Passing the loader in keeps the OS-fs vs. CopyOnWriteFs difference at the caller.

I standardized the diagnostic wording on cmd's semicolon form ("Failed to load the root module; %w"), where langserver previously used a colon.

Testing

Adds tflint/runner_set_test.go: a table test that builds a terraform.Loader over an in-memory afero fixture and asserts module-runner count, variable resolution (auto-loaded and explicit varfiles), and annotation attachment. This pipeline could previously only be exercised through the CLI binary or the LSP integration harness.

[Copilot]

Pull request overview

This PR extracts the common “load → annotate → vars → build → runners” setup logic into a shared tflint.BuildRunners helper, and updates both the CLI inspector and the language server to use that single implementation. This reduces duplication while keeping higher-level inspection/check loops (plugin lifecycle, parallel module checks, diagnostics conversion, autofix behavior) in their respective callers.

Changes:

• Added tflint.BuildRunners(loader, config, workingDir, dir) in tflint/runner_set.go to centralize runner setup.
• Routed cmd/inspect.go and langserver/handler.go through BuildRunners, removing duplicate setup code.
• Added tflint/runner_set_test.go to exercise the runner-setup pipeline (varfiles, variable resolution, annotations, module runners).

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
tflint/runner_set.go	Introduces shared runner setup function that encapsulates the previously duplicated pipeline.
tflint/runner_set_test.go	Adds coverage for the extracted setup, including varfile loading, annotation extraction, and child module runner creation.
langserver/handler.go	Replaces inline runner setup with a call to tflint.BuildRunners and keeps the langserver’s single-slice iteration behavior.
cmd/inspect.go	Removes setupRunners method and uses tflint.BuildRunners for CLI inspection runner initialization.

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[wata727]

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