tasks: implement execIfModified

[domenkozar]

Fixes #1682
Fixes #1616

For example:

  tasks = {
    "devenv:compile-requirements" = {
      before = [ "devenv:python:virtualenv" ];
      exec = "uv pip compile requirements.in -o requirements.txt";
      execIfModified = [
        "requirements.in"
        "requirements.txt"
      ];
    };
  };

cc @rawkode

[cloudflare-workers-and-pages]

Deploying devenv with    Cloudflare Pages

Latest commit:	21f7860
Status:	✅  Deploy successful!
Preview URL:	https://a8e0789d.devenv.pages.dev
Branch Preview URL:	https://tasks-exec-if-modified.devenv.pages.dev

View logs

[sandydoo]

This is a subset of the eval cache implementation with a few task-specific naming differences. I'm wondering whether it would make sense to extract the database and file checking parts of eval-cache and build both eval-cache and task-cache on top of a shared base.

[domenkozar]

This is a subset of the eval cache implementation with a few task-specific naming differences. I'm wondering whether it would make sense to extract the database and file checking parts of eval-cache and build both eval-cache and task-cache on top of a shared base.

I was thinking the same, ideally we'd be using the same database for all the caching.

[domenkozar]

@sandydoo I've created devenv-cache-core that shared the sqlite logic and file operations and reused it in both crates :)