refactor: apply code style and linter improvements across Go files

[appleboy]

• Refactor file locking parameters into top-level constants in filelock.go for improved maintainability.
• Replace duplicated error handling durations and retry settings with reusable constants in file locking logic.
• Update for-loops to use range-based iteration on integer variables for better Go style in tests and concurrency code.
• Replace usage of fmt.Errorf with errors.New for static error strings.
• Prefer named http.Method* constants over string literals for HTTP methods in main.go and tests.
• Use map[string]any instead of map[string]interface{} for type declarations.
• Add and fine-tune multiple linters and their configurations in .golangci.yml; introduce new linter settings and rules, improve output formatting, and remove several linters no longer used.
• Update comments or linter ignore statements for greater clarity.
• Use a min() helper rather than manual interval capping in polling logic.

[Copilot]

Pull request overview

This PR applies comprehensive code style and linter improvements across the Go codebase, modernizing the code to use Go 1.22+ features and enforcing consistent patterns through enhanced linter configuration.

Changes:

• Extracted magic numbers and durations in file locking logic into top-level constants for better maintainability
• Replaced fmt.Errorf with errors.New for static error strings to improve efficiency and semantic clarity
• Updated HTTP method calls to use named http.Method* constants instead of string literals
• Modernized for-loops to use Go 1.22+ range-based iteration over integers
• Replaced map[string]interface{} with map[string]any throughout test files
• Replaced manual interval capping logic with the builtin min() helper function
• Enhanced .golangci.yml with additional linters (modernize, usestdlibvars, revive, etc.) and stricter nolint requirements
• Added explanation to nolint directive for improved documentation

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
filelock.go	Extracted lock retry and timeout parameters into top-level constants; converted loop to use range-based iteration
main.go	Replaced fmt.Errorf with errors.New for static strings; updated HTTP methods to use constants; simplified interval capping with min()
main_test.go	Replaced map[string]interface{} with map[string]any; converted loops to range-based iteration; added explanation to nolint comment
polling_test.go	Replaced map[string]interface{} with map[string]any; updated HTTP method check to use constant
filelock_test.go	Converted loop to use range-based iteration
.golangci.yml	Added multiple linters (bidichk, modernize, usestdlibvars, revive, etc.); configured stricter nolint rules requiring explanations; removed unused linters; added timeout configuration

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