feat: Add configurable ignore patterns for file watcher

This PR adds support for configurable ignore patterns in the SST file watcher to prevent infinite rebuild loops caused by build artifacts.

When using SST with Python projects (or other build systems), package builds create artifacts like .egg-info directories and functions-*.tar.gz files that trigger SST's file watcher, causing infinite rebuild loops during sst dev. Makes local dev not work.

So, this:

• Added ignore field to the App struct in pkg/project/project.go
• Modified file watcher in cmd/sst/mosaic/watcher/watcher.go to accept custom ignore patterns
• Updated cmd/sst/mosaic.go to pass ignore patterns from project config
• Added ignore filtering in AWS function service to prevent rebuilds on ignored files
• Uses substring matching for pattern detection (e.g., ".egg-info" matches any path containing .egg-info)

Configure ignore patterns in your sst.config.ts:

export default $config({
  app(input) {
    return {
      name: "my-app",
      home: "aws",
      ignore: [".egg-info", "functions-"] // Ignore Python build artifacts
    };
  }
});

I tested:

- Verified no crash loops with Python build artifacts
- Confirmed successful deployment and working Lambda endpoints
- Tested that ignored files don't trigger rebuilds during sst dev

While this is pending, SST watcher ignores . prefixed files and symlinks: https://github.com/sst/sst/blob/v3.17.23/cmd/sst/mosaic/watcher/watcher.go#L38

This may be acceptable to some.

E.g. Rust runtime "too many open files" is solved by renaming ./target to ./.target: https://github.com/sst/sst/issues/6237#issuecomment-3573027872

@MarkMarine catching up on this.. do u mind resolving the conflicts? I can merge after that.