chore: Format code with golangci-lint fmt

[alexandear]

• Change script/fmt.sh to use the golangci-lint fmt command. Internally, it uses gofmt, gci, gofumpt, goimports simultaneously.
• Set gci.sections, gofumpt.extra-rules in golangci-lint config and reformat examples.

Inspired by discussion comments in #3938.

[merchantmoh-debug]

@alexandear - Genius. Very good idea.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.45%. Comparing base (1c42933) to head (cde61aa).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3949   +/-   ##
=======================================
  Coverage   92.45%   92.45%           
=======================================
  Files         203      203           
  Lines       14980    14980           
=======================================
  Hits        13850    13850           
  Misses        927      927           
  Partials      203      203           

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[gmlewis]

I may be an old-school Go developer, but I much prefer the grouping of all external imports into a single sorted bunch so that I don't have to visually search multiple bunches to find what I'm looking for.

Is there any way to give the new formatter a flag that preserves this "feature" (in my humble opinion)?

[merchantmoh-debug]

@gmlewis - I can answer that.

Yes, the tool absolutely supports the "Old School" grouping you prefer (Single sorted bunch for all non-standard imports).

Currently, the config defines 3 sections, which forces the split you're seeing:

standard
default (Third-party)
prefix(github.com/google/go-github/) (Internal)
To restore the single "External+Internal" bunch (preserving just the 2-block layout: Standard + Everything Else), we just need to remove the prefix section.

The Config Fix (.golangci.yml):

linters-settings:
gci:
sections:
- standard # Section 1: Standard Lib
- default # Section 2: Everything else (External + Internal sorted together)
# - prefix(github.com/google/go-github/) <--- Removing this merges it into 'default'
This configuration tells the linter to treating everything non-standard as one group, eliminating the "visual search" through multiple bunches.

[alexandear]

@gmlewis reverted. By default, gci groups imports into two sections: std and default.

[gmlewis]

Thank you, @alexandear and @merchantmoh-debug!
LGTM.
Merging.