Fix offline setting not being respected

[jensens]

Summary

Fixes #34: The offline configuration setting and --offline CLI flag are now properly respected to prevent VCS fetch/update operations.

Current Status: Demonstrating the Bug

Failing Test

The first commit adds test_offline_prevents_vcs_operations() that demonstrates the issue:

Test scenario:

1. Create repo and perform initial checkout
2. Add new content to remote repo
3. Try to update with offline=True
4. FAILS: Update happens anyway, fetching new content

Error:

AssertionError: assert {PosixPath('.../bar')} == {PosixPath('.../foo')}
Extra items in the left set:
PosixPath('.../bar')

The test shows that "bar" was fetched even though offline=True was set.

Root Cause

There are two separate bugs that both need fixing:

Bug #1: main.py ignores offline configuration (line 92)

if not args.no_fetch:
    fetch(state)

Problem: Only checks --no-fetch CLI flag, completely ignores the configuration's offline setting.

What happens:

• User sets offline = true in mx.ini → fetch() is still called
• User uses --offline CLI flag → sets config offline=true, but fetch() is still called
• Only --no-fetch CLI flag actually skips fetch()

Bug #2: processing.py hardcodes offline=False (line 201)

workingcopies.checkout(
    sorted(packages),
    verbose=False,
    update=True,
    submodules="always",
    always_accept_server_certificate=True,
    offline=False,  # BUG: Should use state.configuration.settings
)

Problem: Even if we fix Bug #1, the fetch() function itself passes offline=False hardcoded.

Next Steps

• Fix main.py to check offline setting before calling fetch()
• Fix processing.py to pass offline setting from configuration
• Verify test passes
• Run linting
• Update CHANGES.md
• Mark PR ready when CI is green

Test Plan

# Currently fails:
pytest tests/test_git.py::test_offline_prevents_vcs_operations -v

# After fix, should pass