Enhance and harden CI/CD workflows

[das-Abroxas]

These changes strengthens automated validation across the workspace and makes crate releases safer and more predictable. Adds dependency and license policy checks while standardizing Rust tooling and coverage configuration.

Changes

• Added CI jobs for tests, formatting, Clippy, cargo-deny, and GitHub Actions linting
• Improved release validation for SemVer tags, main-branch ancestry, and package versions
• Added package, dry-run, and retry-safe publishing checks for pithos_lib and pithos
• Standardized Rust 1.88 as the workspace minimum supported version
• Added cargo-deny configuration and Apache/MIT license files
• Updated Codecov thresholds and coverage generation
• Renamed the CI workflow file to ci.yaml
• Fixed Clippy/actionlint warnings

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.07%. Comparing base (f9264e1) to head (caaf99b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #25   +/-   ##
=======================================
  Coverage   69.07%   69.07%           
=======================================
  Files          17       17           
  Lines        2985     2985           
=======================================
  Hits         2062     2062           
  Misses        923      923           

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[greatfireball]

LGTM