Simplify now() to use new DateTimeImmutable('now', $utc) directly, avoiding costly microtime+createFromFormat roundtrip and locale-sensitive float formatting

[gustavofreze]

No description provided.

[Copilot]

Pull request overview

This PR optimizes Instant::now() by constructing DateTimeImmutable('now', $utc) directly (removing the microtime() → sprintf() → createFromFormat() roundtrip), and updates repository/tooling metadata and contributor guidance.

Changes:

• Simplify Instant::now() implementation and remove the no-longer-needed microsecond format constant.
• Change timezone identifier validation to call DateTimeZone::listIdentifiers() directly (and remove the cached helper).
• Refresh project tooling/config/docs (Composer config/scripts, Infection mutators, Makefile targets, repo dotfiles, and new .claude/ rule docs).

Reviewed changes

Copilot reviewed 15 out of 16 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/Timezone.php	Replaces cached identifier list with direct DateTimeZone::listIdentifiers() call and removes helper.
src/Instant.php	Simplifies now() to new DateTimeImmutable('now', $utc); removes microsecond format constant.
infection.json.dist	Changes disabled mutator from AssignCoalesce to ProtectedVisibility.
composer.json	Updates package metadata, bumps dependencies, adds composer-normalize, reorganizes scripts/config.
README.md	Updates overview wording to reflect library scope and immutability/value-object contract.
Makefile	Runs composer normalize in configure, adds show-outdated, updates help output.
.gitignore	Expands ignored IDE/agent artifacts; ignores composer.lock and coverage/build outputs.
.github/copilot-instructions.md	Adds Copilot guidance pointing to .claude rules as source of truth.
.gitattributes	Adds LF normalization and a clearer export-ignore list for Packagist tarballs.
.editorconfig	Adds editor defaults (LF, trimming, indent rules, Makefile tabs).
.claude/rules/php-library-testing.md	Adds PHPUnit + BDD Given/When/Then and strict coverage/mutation requirements.
.claude/rules/php-library-modeling.md	Adds library architecture/modeling rules and public/internal API boundary guidance.
.claude/rules/php-library-documentation.md	Adds README/documentation standards (TOC, badges, examples, FAQ, etc.).
.claude/rules/php-library-code-style.md	Adds semantic PHP style rules (naming, comparisons, no else, etc.).
.claude/rules/github-workflows.md	Adds workflow structure/security/style rules for GitHub Actions.
.claude/CLAUDE.md	Adds project meta-guidance + required validation commands after changes.