chore(de): replace x/ slog with std slog

[SVilgelm]

Update logging to use the new standard library slog package
instead of golang.org/x/exp/slog. Replace imports across
config.go, main.go, log.go to import "log/slog" and remove the
x/exp dependency from go.mod and go.sum. Also bump go toolchain
version to 1.25 and fix a minor comment wording ("a grace period").
These changes simplify dependencies and adopt the stable slog
implementation from the standard library.

[Copilot]

Pull Request Overview

This PR migrates the codebase from using the experimental golang.org/x/exp/slog package to the standard library log/slog package. This change adopts the stable slog implementation that became available in Go's standard library and simplifies the project's dependency tree.

• Replace all imports of golang.org/x/exp/slog with log/slog
• Remove the experimental slog dependency from go.mod
• Update Go toolchain version to 1.25

Reviewed Changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated no comments.

File	Description
main.go	Updated slog import and fixed comment grammar
log.go	Updated slog import to use standard library
config.go	Updated slog import to use standard library
go.mod	Removed x/exp dependency and bumped Go version

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