[API] introduce the logic of artifact deletion considering artifact

[truddy0]

What this PR does

This is the 2nd PR of model artifact reuse feature #409 .

Introduce the logic of artifact deletion considering artifact attribute in configmap
Deletion logic:

1. if the artifact directory does not have any symbolic link pointed to, remove the artifact directory. Otherwise, skip deleting artifact directory
2. if the parent artifact directory is dangling after the last child is deleted, delete the parent artifact directory after the last child artifact is deleted
   Change internal contract:
3. the arfiact attribute on configmap is

type Artifact struct {
	Sha string `json:"sha"` // sha string fetched from HuggingFace
	// parent model name -> parent model artifact storage path
	ParentPath    map[string]string `json:"parentPath"`
	ChildrenPaths []string          `json:"childrenPaths"` // an array of children paths
}

Why we need it

efficiently remove the artifact directory without interfering with the usage

How to test

Test ID	Context	Test Action	Expected Result	Test Evidence
Test 1	Parent model has 1 child	Delete parent model	Parent model artifact is preserved	Test 1 in test evidence file
Test 2	Parent model has multiple children	Delete a child model while parent still has other children	Child artifact directory is deleted; parent artifact directory is preserved; parent CM entry is updated (kid1 removed, kid2 remains)	Test 2 in test evidence file
Test 3	Parent model CR is already deleted; parent still has more than 1 children	Delete child model	Child artifact directory is deleted; parent artifact directory is preserved	Test 3 in test evidence file
Test 4	Parent model CR is already deleted; this is the last remaining child	Delete child model	Child artifact directory is deleted; parent artifact directory is deleted as well	Test 4 in test evidence file

testEvidence-ModelDeletion.txt

Checklist

• Tests added/updated (if applicable)
• Docs updated (if applicable)
• make test passes locally

[gemini-code-assist]

Warning

You have reached your daily quota limit. Please wait up to 24 hours and I will start processing your requests again!

[slin1237]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces significant logic for artifact deletion and reuse, including a parent-child relationship for artifacts stored in the ConfigMap. The changes are extensive, touching config parsing, ConfigMap reconciliation, and the main gopher logic. The code is well-refactored into smaller, more manageable functions, especially the new deletion logic in gopher.go and the robust ConfigMap update mechanisms in configmap_reconciler.go. The accompanying tests are thorough and cover many new scenarios and edge cases. I have a couple of minor suggestions for improvement.

[gemini-code-assist]

There's a typo in the log message. "profress" should be "progress".

Suggested change

	c.logger.Infof("will update model profress in configmap for key %s", key)
	c.logger.Infof("will update model progress in configmap for key %s", key)

[truddy0]

fixed the typo

[gemini-code-assist]

The ChildrenPaths slice is now assigned directly, whereas previously a copy was made using append. While this might be safe in the current context as the resulting ModelConfig is short-lived, it's generally safer to create a copy to prevent potential side effects if the source or destination slice is modified elsewhere. This makes the code more robust against future changes.

Suggested change

	ChildrenPaths: currentArtifact.ChildrenPaths,
	ChildrenPaths: append([]string(nil), currentArtifact.ChildrenPaths...),

[truddy0]

introduce logics to handle edge case for both parentPath and chidlrenPaths