Improve performance: fix defer-in-loop leaks, eliminate redundant operations, add container caching

[Copilot]

Identified and fixed multiple performance issues and resource leaks across Dagger modules.

Container Setup Optimization

• helm/container.go: Removed duplicate apk add call, added temp file cleanup after tool installations, added container caching via cachedContainer field
• git/container.go: Combined 6 individual sh -c commands into single script
• kcl/container.go: Combined apt-get update && install with --no-install-recommends and apt cache cleanup
• linting/container.go: Combined gem install and pip install into single command with --no-cache-dir

Duplicate Work Elimination

• go/test.go: Was running tests twice (once with -v, once with -cover). Now runs once with both flags.

// Before: ran tests twice
testOutput, _ := container.WithExec([]string{"go", "test", "-v", testArg}).Stdout(ctx)
coverageOutput, _ := container.WithExec([]string{"go", "test", "-cover", testArg}).Stdout(ctx)

// After: single pass
testOutput, err := container.WithExec([]string{"go", "test", "-v", "-cover", testArg}).Stdout(ctx)

Resource Leak Fixes

• hugo/helpers.go: Fixed defer-in-loop bug in downloadImages() - defers were accumulating until function return
• templating/file.go, string.go: Same defer-in-loop fix, extracted downloadURLContent() helper

// Before: defer inside loop accumulates calls
for _, url := range urls {
    resp, _ := http.Get(url)
    defer resp.Body.Close()  // BUG: defers pile up
}

// After: helper function scopes defer correctly
func downloadSingleImage(url, destDir string) error {
    resp, _ := http.Get(url)
    defer resp.Body.Close()  // OK: runs at helper return
    // ...
}

Bug Fixes

• ansible/container.go: baseImage parameter was being ignored in favor of hardcoded value

Original prompt

Identify and suggest improvements to slow or inefficient code

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