feat(error): enhance error logging with tracing integration

[Soroushsrd]

This PR enhances error logging in Cot by implementing structured logging with the tracing crate. The goal is to improve observability and enable better integration with OpenTelemetry for monitoring errors in production services.

Changes:

• Implement structured error logging with tracing spans
• Add request context and metadata to error logs
• Include backtrace information in error spans
• Add comprehensive test coverage for logging functionality
• Maintain backwards compatibility with existing error pages

Added new tests that verify:

• Error logging with request context
• Error logging without request context
• Panic logging
• Not found logging
• Integration with error page handlers

related Issues
Implements better error monitoring as discussed in issue #160

• Tests added for new functionality (some might be redundant)
• Code follows project style guidelines
• All tests passing
• No new warnings

[Soroushsrd]

The CI test failure appears to be due to a dependency (hybrid-array-0.3.0) requiring edition2024, which isn't stable in Cargo 1.84.1. This is unrelated to my changes for error logging.

Error message:

error: failed to parse manifest at `/Users/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/hybrid-array-0.3.0/Cargo.toml`
Caused by:
  feature `edition2024` is required

The CI test failure is actually related to this transitive dependency chain:
hmac -> digest -> crypto-common -> hybrid-array

We could:

1. Pin hmac to a version that uses older versions of these dependencies
2. Pin digest to a version before it started using crypto-common 0.2.0-rc.1
3. Update the project's MSRV to a version that supports edition2024

Ill be happy to do any of them. Please let me know. @m4tx

[m4tx]

Updating our MSRV (so option 3) to 1.85 is fine; we'll want to upgrade to edition 2024 soon anyways, and maintaining a stable MSRV isn't super important at this stage of the project development anyway. Thanks!

[codecov]

Codecov Report

Attention: Patch coverage is 95.31250% with 6 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
cot/src/error_page.rs	95.31%	2 Missing and 4 partials ⚠️

Flag	Coverage Δ
rust	78.55% <95.31%> (+0.17%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
cot/src/error_page.rs	89.42% <95.31%> (+2.80%)	⬆️

[m4tx]

I took the liberty of fixing the dependency issue, since it was causing problems elsewhere, too (see #187).

The change looks good to me; please ensure the macro invocations are consistently formatted (see my review comments), and please fix the cargo fmt issues, and then it'll be ready to merge!

[Soroushsrd]

Thank you Ill keep that in mind for future contributions.

[m4tx]

LGTM, thanks a lot for the contribution!