feat(data-dictionary): co-locate dialect packages and consolidate domain SQL

[cofin]

Description

Refactors the data dictionary subsystem in sqlspec/data_dictionary/ to co-locate Python dialect modules and SQL query files into package directories per database engine.

Changes Included

1. Co-located Dialect Packages: Converts sqlspec/data_dictionary/dialects/<dialect>.py into package directories sqlspec/data_dictionary/dialects/<dialect>/ containing config.py (defines <DIALECT>_CONFIG) and __init__.py (re-exports config & helpers).
2. Domain SQL Subdirectories: Places domain .sql query files (columns.sql, tables.sql, indexes.sql, etc.) inside sqlspec/data_dictionary/dialects/<dialect>/sql/.
3. Loader Refactoring: Updates DataDictionaryLoader in _loader.py to lazy-load domain .sql files via importlib.resources.files(f"sqlspec.data_dictionary.dialects.{dialect}.sql").joinpath(f"{domain}.sql").
4. Directory Cleanup: Removes the legacy sqlspec/data_dictionary/sql/ directory tree.

Quality Gates

• make lint passed (ruff lint, format, mypy, pyright, slotscheck, codespell, zizmor).
• uv run pytest tests/unit/data_dictionary/ passed (125/125 unit tests green).

[codecov-commenter]

Codecov Report

❌ Patch coverage is 67.32026% with 50 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.39%. Comparing base (908004c) to head (7e3e991).

Files with missing lines	Patch %	Lines
sqlspec/adapters/adbc/data_dictionary.py	44.82%	15 Missing and 1 partial ⚠️
sqlspec/data_dictionary/_loader.py	57.69%	8 Missing and 3 partials ⚠️
sqlspec/adapters/arrow_odbc/data_dictionary.py	50.00%	8 Missing and 1 partial ⚠️
sqlspec/driver/_common.py	60.00%	3 Missing and 1 partial ⚠️
sqlspec/adapters/bigquery/data_dictionary.py	40.00%	3 Missing ⚠️
sqlspec/adapters/mysqlconnector/data_dictionary.py	71.42%	2 Missing ⚠️
sqlspec/adapters/aiomysql/data_dictionary.py	66.66%	1 Missing ⚠️
sqlspec/adapters/aiosqlite/data_dictionary.py	66.66%	1 Missing ⚠️
sqlspec/adapters/asyncmy/data_dictionary.py	66.66%	1 Missing ⚠️
sqlspec/adapters/spanner/data_dictionary.py	0.00%	1 Missing ⚠️
... and 1 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #688      +/-   ##
==========================================
- Coverage   77.41%   77.39%   -0.03%     
==========================================
  Files         476      486      +10     
  Lines       68266    68278      +12     
  Branches     9403     9405       +2     
==========================================
- Hits        52849    52844       -5     
- Misses      12013    12024      +11     
- Partials     3404     3410       +6     

Flag	Coverage Δ
integration	60.86% <52.94%> (-0.04%)	⬇️
py3.10	75.70% <67.32%> (-0.02%)	⬇️
py3.11	75.72% <67.32%> (-0.02%)	⬇️
py3.12	75.72% <67.32%> (-0.02%)	⬇️
py3.13	75.72% <67.32%> (-0.02%)	⬇️
py3.14	76.60% <67.32%> (-0.03%)	⬇️
unit	65.02% <58.82%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
sqlspec/adapters/asyncpg/data_dictionary.py	70.25% <100.00%> (ø)
...spec/adapters/cockroach_asyncpg/data_dictionary.py	42.02% <100.00%> (ø)
...spec/adapters/cockroach_psycopg/data_dictionary.py	37.19% <100.00%> (ø)
sqlspec/adapters/duckdb/data_dictionary.py	62.72% <100.00%> (ø)
sqlspec/adapters/mssql_python/data_dictionary.py	74.64% <100.00%> (ø)
sqlspec/adapters/oracledb/data_dictionary.py	71.79% <100.00%> (ø)
sqlspec/adapters/psqlpy/data_dictionary.py	70.80% <100.00%> (ø)
sqlspec/adapters/psycopg/data_dictionary.py	68.97% <100.00%> (ø)
sqlspec/adapters/pymssql/data_dictionary.py	65.49% <100.00%> (ø)
sqlspec/adapters/pymysql/data_dictionary.py	60.68% <100.00%> (ø)
... and 30 more

... and 3 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.