fix: enable --show-item-count in non-interactive mode (#431)

[ShivamB25]

Problem

The --show-item-count (-C) flag was not working in non-interactive mode (-n). Item counts were not displayed next to entries, unlike in interactive mode.

Solution

• Modified stdout/stdout.go to respect the --show-item-count flag in non-interactive output
• Updated cmd/gdu/app/app.go to properly pass the item count flag to the stdout formatter
• Added comprehensive test coverage in stdout/stdout_test.go to verify item counts display correctly in non-interactive mode

Testing

All tests pass:

• golangci-lint run ✓
• go test -v -covermode=count ./... ✓
• go test -v -race -covermode=atomic -coverprofile=coverage.out ./... ✓

Closes

Closes #431

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.54%. Comparing base (ede21d2) to head (8379c42).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #495      +/-   ##
==========================================
+ Coverage   81.42%   81.54%   +0.11%     
==========================================
  Files          49       49              
  Lines        5126     5158      +32     
==========================================
+ Hits         4174     4206      +32     
  Misses        816      816              
  Partials      136      136              

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[ShivamB25]

Addressed the Codecov patch-coverage gaps with targeted tests and pushed commit 8379c42.

What was added:

• non-interactive app propagation test for --show-item-count (covers createUI() branch in cmd/gdu/app/app.go)
• stdout color-path test for showItemCnt + UseColors (covers printItem() branch in stdout/stdout.go)

Validation run locally:

• golangci-lint run
• go test -v -covermode=count ./...
• go test -v -race -covermode=atomic -coverprofile=coverage.out ./...

Please re-check Codecov on this latest head.