refactor(BA-2136): Replace deprecated pkg_resources with importlib

[achimnol]

resolves #5525 (BA-2136)

[Copilot]

Pull Request Overview

This PR replaces the deprecated pkg_resources module with importlib.resources to modernize resource access in the Backend.AI agent codebase, addressing compatibility with Python 3.12+ where pkg_resources is deprecated.

Key changes:

• Replace pkg_resources.resource_filename() calls with files().joinpath() pattern from importlib.resources
• Add from importlib.resources import files imports across affected modules
• Remove import pkg_resources statements

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/ai/backend/agent/stage/kernel_lifecycle/docker/scratch.py	Updated dotfile cloning to use importlib for resource access
src/ai/backend/agent/stage/kernel_lifecycle/docker/mount/krunner.py	Migrated krunner artifact path resolution and file access
src/ai/backend/agent/kubernetes/utils.py	Updated container image path resolution
src/ai/backend/agent/kubernetes/kernel.py	Migrated krunner environment preparation and file copying
src/ai/backend/agent/kubernetes/agent.py	Updated dotfile cloning in Kubernetes agent
src/ai/backend/agent/docker/utils.py	Updated container image path resolution
src/ai/backend/agent/docker/kernel.py	Migrated krunner environment and metadata handling
src/ai/backend/agent/docker/agent.py	Updated dotfile cloning and krunner file resolution
src/ai/backend/agent/agent.py	Updated krunner info retrieval and artifact path resolution
changes/.fix.md	Added changelog entry

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[Copilot]

The relative path navigation using "../runner" could be fragile. Consider using a more explicit package reference or verify this path structure is guaranteed to remain stable.

Suggested change

	artifact_path = Path(str(files("ai.backend.agent").joinpath("../runner")))
	kernel_path = Path(str(files("ai.backend.agent").joinpath("../kernel")))
	helpers_path = Path(str(files("ai.backend.agent").joinpath("../helpers")))
	base_path = Path(__file__).parent.parent # ai/backend/agent/
	artifact_path = base_path / "runner"
	kernel_path = base_path / "kernel"
	helpers_path = base_path / "helpers"

[Copilot]

Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.