fix(#626): repair migration CLI quickstart

[cofin]

Summary

• accept both module.attribute and module:attribute configuration references at the SQLSpec config resolver boundary
• replace the broken migration workflow GIF with a complete, tested SQLite quickstart
• document CLI, environment-variable, and pyproject.toml configuration discovery

Details

The generic import helper remains unchanged. The quickstart exports a SqliteConfig, uses version_table_name, and performs no import-time migration. Its copied database.py is exercised through the exact documented database:database_config reference and the show-config, init, create-migration, upgrade, and current-revision commands.

Closes #626.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.25%. Comparing base (a3a3012) to head (12b4a0d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #670   +/-   ##
=======================================
  Coverage   77.25%   77.25%           
=======================================
  Files         475      475           
  Lines       67901    67906    +5     
  Branches     9335     9336    +1     
=======================================
+ Hits        52458    52463    +5     
  Misses      12039    12039           
  Partials     3404     3404           

Flag	Coverage Δ
integration	60.94% <85.71%> (+0.13%)	⬆️
py3.10	75.57% <100.00%> (-0.01%)	⬇️
py3.11	75.58% <100.00%> (+<0.01%)	⬆️
py3.12	75.59% <100.00%> (+<0.01%)	⬆️
py3.13	75.59% <100.00%> (+11.11%)	⬆️
py3.14	76.46% <100.00%> (+<0.01%)	⬆️
unit	64.78% <100.00%> (+<0.01%)	⬆️

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Files with missing lines	Coverage Δ
sqlspec/utils/config_tools.py	93.12% <100.00%> (+0.27%)	⬆️

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