feat: add configurable temp directory to resolve Windows access denied errors

[sergio-sisternes-epam]

Description

Add temp-dir configuration key so users can override the system temporary directory used during apm install. This resolves [WinError 5] Access is denied errors in corporate Windows environments where endpoint security or Group Policy restricts access to %TEMP%.

Fixes #624

Changes

• src/apm_cli/config.py -- Add get_temp_dir(), set_temp_dir(), get_apm_temp_dir() with resolution chain: APM_TEMP_DIR env var > config file > system default
• src/apm_cli/commands/config.py -- Wire temp-dir into set/get/display subcommands
• src/apm_cli/deps/github_downloader.py -- Use get_apm_temp_dir() at all 4 temp creation sites + catch PermissionError/OSError with actionable message
• src/apm_cli/bundle/unpacker.py, runtime/manager.py, commands/update.py -- Wire dir=get_apm_temp_dir() at remaining temp sites
• Docs -- CLI reference, skills resource, CHANGELOG updated

Usage

# Set a custom temp directory
apm config set temp-dir C:\apm-temp

# Check current setting
apm config get temp-dir

# Or use environment variable (takes precedence)
export APM_TEMP_DIR=/tmp/apm-work

Type of change

• Bug fix
• New feature
• Documentation
• Maintenance / refactor

Testing

• Tested locally
• All existing tests pass (3776 passed)
• Added tests for new functionality (51 new tests across 2 files)

[Copilot]

Pull request overview

Adds a user-configurable temporary directory override (env var + persisted config + CLI wiring) so apm install and other operations can avoid locked-down %TEMP% locations in corporate Windows environments.

Changes:

• Introduces get_temp_dir(), set_temp_dir(), and get_apm_temp_dir() with APM_TEMP_DIR > config file > system default resolution.
• Wires temp-dir into apm config show/get/set and routes temp creation sites to use the effective temp directory.
• Adds unit tests + updates docs and CHANGELOG.md to document the new configuration key.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
src/apm_cli/config.py	Adds temp-dir config getters/setters and effective temp dir resolution logic.
src/apm_cli/commands/config.py	Exposes temp-dir via apm config show/get/set flows.
src/apm_cli/deps/github_downloader.py	Uses configurable temp dir for git temp work; adds access-denied error messaging.
src/apm_cli/bundle/unpacker.py	Extract temp dir for bundle unpacking now respects configured temp base.
src/apm_cli/runtime/manager.py	Embedded runtime scripts now run in temp dirs under the configured base.
src/apm_cli/commands/update.py	Update installer temp script is created under the configured temp base.
tests/unit/test_github_downloader_temp_dir.py	Adds tests around access-denied handling in subdirectory downloads.
tests/unit/test_config_command.py	Adds tests for config display + config/temp-dir resolution helpers + CLI config get/set temp-dir.
docs/src/content/docs/reference/cli-commands.md	Documents temp-dir in CLI reference and usage examples.
packages/apm-guide/.apm/skills/apm-usage/commands.md	Updates skill resource command list to mention temp-dir.
CHANGELOG.md	Adds an Unreleased entry for the new temp-dir configuration key.