feat(tracing): migrate logging to tracing

[ognis1205]

Description

This PR migrates the logging implementation from env_logger to tracing.

The migration preserves the existing log format while extending it to include span information, enabling more structured and contextual logging without changing the default user experience.

Motivation and Context

This change is motivated by the following discussion and issues:

• Review of log level usage: promote certain trace! logs to info! to improve observability #1191
• Migrate logging from env_logger to tracing + tracing-subscriber #1268

The goal is to modernize git-cliff's logging infrastructure by adopting tracing, while maintaining backward compatibility and avoiding unnecessary complexity in the core crate.

What Has Changed

• The logger has been updated to emit spans in a format consistent with the existing log output.
• Span instrumentation is applied only to methods that affect the changelog generator's semantics (e.g. changelog, release, and commit processing).
• git-cliff-core now depends on tracing behind a feature flag.
  • When the feature is disabled, the behavior is unchanged and only the existing log output is produced.
  • When the feature is enabled, spans are created and included in the output.
• Remote metadata progress reporting has been fully migrated to a tracing-based implementation using tracing-indicatif.
• The progress bar implementation is intentionally kept simple.
  • While richer progress reporting is possible with tracing, implementing such behavior cleanly would require API changes outside of git-cliff-core.
  • Given the current API design, this PR avoids introducing additional complexity and leaves room for future design discussions.

How Has This Been Tested?

• Existing unit tests were run.
• Logging output was verified manually.

Screenshots / Logs (if applicable)

N/A

Types of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (no code change)
• Refactor (refactoring production code)
• Other

Checklist:

• My code follows the code style of this project.
• I have updated the documentation accordingly.
• I have formatted the code with rustfmt.
• I checked the lints with clippy.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 77 lines in your changes missing coverage. Please review.
✅ Project coverage is 43.69%. Comparing base (97b0322) to head (b53b100).

Files with missing lines	Patch %	Lines
git-cliff/src/logger.rs	0.00%	72 Missing ⚠️
git-cliff-core/src/changelog.rs	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1308      +/-   ##
==========================================
+ Coverage   43.40%   43.69%   +0.30%     
==========================================
  Files          23       23              
  Lines        2247     2232      -15     
==========================================
  Hits          975      975              
+ Misses       1272     1257      -15     

Flag	Coverage Δ
unit-tests	43.69% <0.00%> (+0.30%)	⬆️

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[orhun]

10 seconds ago I was happy that my GitHub notifications were clear and then Shingo comes in with a crazy PR!!!!!

+0 additions -0 deletions though. Love it. LGTM

[orhun]

planning to do any progress on this soon? (added to 2.12.0 milestone)

[ognis1205]

planning to do any progress on this soon? (added to 2.12.0 milestone)

Yeah, I'm planning to open a PR later this week.
Does that timeline work for the 2.12.0 milestone?

[orhun]

yup, 2.12.0 will happen in 2026 :)
so we have a whole year!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[ognis1205]

Sorry for the delay. I'll start working on this PR today.

[orhun]

No worries at all!

[ognis1205]

This is ready for review now @orhun .

I consider this a first draft, and there are likely areas open for discussion. When you have time, I'd really appreciate your thoughts and feedback.

[ognis1205]

TODO:

• Replace all ASCII color codes with owo_colors.
• Consider how to handle Windows and non-TTY environments (this may also have been an issue in the previous implementation).