fix: allow mining directories without local mempalace.yaml

[mvanhorn]

What does this PR do?

Changes load_config() in miner.py to return sensible defaults instead of sys.exit(1) when no mempalace.yaml exists in the source directory.

The bug: mempalace mine ~/chats/ fails with ERROR: No mempalace.yaml found when the user init'd in a different directory (~/projects/myapp). The miner requires mempalace.yaml in every source directory, but users expect to init once and mine from anywhere.

The fix: when no yaml is found, derive a wing name from the directory basename and use a single "general" room. Prints an informational message instead of crashing.

Closes #14.

How to test

# Create a directory with no mempalace.yaml
mkdir /tmp/test-mine
echo "some content" > /tmp/test-mine/file.txt
mempalace mine /tmp/test-mine
# Should work instead of crashing

Or run the new test:

pytest tests/test_miner.py::test_load_config_uses_defaults_when_yaml_missing -v

Checklist

• Tests pass (python -m pytest tests/ -v)
• No hardcoded paths
• Linter passes (ruff check .)

This contribution was developed with AI assistance (Codex).

[neocybereth]

"The fix: when no yaml is found, derive a wing name from the directory basename and use a single "general" room. Prints an informational message instead of crashing." -- what does the general informational message look like out of curiosity?

[mvanhorn]

It prints:

  No mempalace.yaml found in /path/to/project — using auto-detected defaults

Then uses the directory basename as the wing name and a single "general" room with all project files.

[bensig]

Conflicts with main. If the mining-without-yaml feature is still needed, a rebased PR against current main would be welcome.

[mvanhorn]

Rebased onto current main and resolved the import conflict in tests/test_miner.py. All 14 miner tests pass and ruff check is clean.

Opened #604 with the rebased branch (couldn't reopen this one). Happy to close it and reopen here instead if you'd prefer. Thanks @bensig!