[Build] Minor refactor build image

[wxdwfc]

This PR mainly do the following:

1. Provide a base image (phos-base-113) to simplify building, e.g., now developer can use make build to quickly build PhOS (w/o building dependencies from scractch) and make server-run to start PhOS workspace without in an interactive container.

2. Separate the build of some packages (e.g., g++) to a separate flag in phos build system to simplify building the container.

3. Move the doc of build from source to a separate markdown file to make the README more concise.

The build has been tested on an A800 server.

[Copilot]

Pull Request Overview

This PR introduces a base Docker image (phos-base-113) to simplify PhOS building, separates package installation from core building through new flags, and reorganizes documentation by moving build instructions to a dedicated markdown file.

• Adds a new Dockerfile and Makefile for containerized builds with pre-built dependencies
• Introduces -p and -b flags to separate package installation from PhOS building
• Moves comprehensive build documentation from README to a separate markdown file

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
scripts/utils/get_root_dir.sh	Enhanced to handle non-git environments gracefully
scripts/build_scripts/main.go	Added new flags for controlling package installation and building phases
scripts/build_scripts/cuda.go	Moved NCCL installation logic and separated package vs build phases
scripts/build_scripts/pos.go	Commented out NCCL installation (moved to cuda.go)
dockerfiles/build_113.Dockerfile	New Dockerfile for creating base image with pre-built dependencies
Makefile	New Makefile providing convenient targets for containerized operations
README.md	Simplified to reference external documentation
docs/docs/getting_started/build_from_source.md	Comprehensive build documentation moved from README

[Copilot]

[nitpick] The condition changed from cmdOpt.DoBuild to cmdOpt.DoPackage but this affects a large block of package installation code. Consider adding a comment explaining this separation of concerns between package installation and building phases.

Suggested change

	// ==================== Prepare ====================
	// ==================== Prepare ====================
	// The following block installs necessary packages and tools required for the packaging phase.
	// This separation ensures that package installation is only performed when packaging is requested,
	// avoiding unnecessary installations during the building phase.

[Copilot]

[nitpick] Large blocks of commented code should be removed rather than left as comments. If this code needs to be preserved for reference, consider adding a brief comment explaining why it's disabled and where the functionality moved to.

Suggested change

	//utils.CheckAndInstallMultiPackagesViaOsPkgManager([]string{
	// "libnccl2=2.26.5-1+cuda12.9", "libnccl-dev=2.26.5-1+cuda12.9",
	//}, logger)
	//if !utils.CheckPackageViaOsPkgManager("libnccl-dev", logger) {
	// utils.UnInstallPackageViaOsPkgManager("libnccl2", logger)
	//}
	//utils.CheckAndInstallPackageViaOsPkgManager("libnccl2=2.26.5-1+cuda12.9", logger)
	//utils.CheckAndInstallPackageViaOsPkgManager("libnccl-dev=2.26.5-1+cuda12.9", logger)
	// The NCCL installation logic has been disabled temporarily.
	// Future updates will handle NCCL installation based on CUDA version.

[Copilot]

The error message 'Not in a git repo.' is written to stdout, which could be problematic if the script output is used by other scripts expecting a directory path. Consider writing error messages to stderr or returning an error code.

Suggested change

	echo "Not in a git repo."
	echo "Not in a git repo." >&2
	exit 1