Add Graphviz DOT table output format

[dbcli-symphony]

Changes

• Adds a dot table format for exporting query results as Graphviz DOT.
• Supports .mode dot, including completion/allowed-format reporting.
• Formats one-column results as DOT nodes, two-column results as directed edges, and additional columns as edge labels.
• Documents dot in the default and test liteclirc format lists.
• Updates the changelog for Exporting as a dot file (How to ?) #238.

Tests

• python -m py_compile litecli/packages/dot_output.py litecli/main.py tests/test_dot_output.py tests/test_main.py
• python -m ruff check litecli/main.py litecli/packages/dot_output.py tests/test_dot_output.py tests/test_main.py
• git diff --check
• Direct DOT formatter assertion script passed