fix(watch): reload compose config before rebuild

[maxpetrusenkoagent]

Summary

• reload the Compose project before a watch rebuild recreates services
• preserve existing watch rebuild behavior while using current compose/env_file data
• add unit coverage for reloading project config and an e2e regression for updated env_file values

Fixes #11003

Test plan

• go test ./pkg/compose -run TestProjectForRebuildReloadsLatestConfig -count=1 -v
• go test ./pkg/compose -run 'TestProjectForRebuildReloadsLatestConfig|TestWatch_Sync' -count=1 -v
• go test ./pkg/compose -count=1
• go test ./cmd/compose -count=1
• go test ./pkg/api ./pkg/compose ./cmd/compose -count=1
• go test -tags e2e ./pkg/e2e -run TestWatchRebuildUsesLatestProjectConfig -count=1 -v could not complete locally because Docker is not running: failed to connect to the docker API at unix:///var/run/docker.sock
• golangci-lint run --build-tags "e2e" ./cmd/compose ./pkg/api ./pkg/compose ./pkg/e2e could not run locally because golangci-lint is not installed
• make lint could not run locally because this Docker CLI has no docker buildx command