feat(builder): consolidate expression construction

[cofin]

Summary

• share window, dialect, column, SQL-object, DDL, and statement-detection helpers
• widen scalar functions to accept builder-native column, wrapper, and case expressions
• add ordered count_over() support and reconcile SQLGlot required expression arguments
• preserve parameter merging for both SQL-text and expression-plus-parameters protocol shapes

Why

Builder expression construction had accumulated parallel normalization, coercion, and parsing paths. Consolidating them reduces drift while preserving rendered SQL and parameter binding.

Impact

count_over() now accepts order_by consistently with other window helpers. Scalar and aggregate helpers accept the same builder-native expression shapes. WHERE, subquery, and JOIN inputs now consistently retain placeholders and values across both supported SQL-object protocols. Materialized views render canonical PostgreSQL WITH DATA and WITH NO DATA clauses.

Validation

• uv run pytest tests/unit/builder/ -q (911 passed)
• make lint
• make type-check
• focused SQL-object protocol, SQLGlot argument-contract, DDL, factory, and select suites

The repository compiled-install target was attempted twice but stalled without diagnostics during the package build; each attempt was interrupted and its temporary build configuration was restored.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 79.54545% with 36 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.95%. Comparing base (6bb5742) to head (407525f).

Files with missing lines	Patch %	Lines
sqlspec/builder/_factory.py	85.88%	12 Missing ⚠️
sqlspec/builder/_parsing_utils.py	70.96%	5 Missing and 4 partials ⚠️
sqlspec/builder/_select.py	52.63%	6 Missing and 3 partials ⚠️
sqlspec/builder/_ddl.py	82.14%	4 Missing and 1 partial ⚠️
sqlspec/builder/_join.py	80.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #639      +/-   ##
==========================================
+ Coverage   76.82%   76.95%   +0.13%     
==========================================
  Files         473      473              
  Lines       66108    66076      -32     
  Branches     9821     9799      -22     
==========================================
+ Hits        50785    50850      +65     
+ Misses      12031    11956      -75     
+ Partials     3292     3270      -22     

Flag	Coverage Δ
integration	60.06% <28.97%> (+0.02%)	⬆️
py3.10	75.21% <79.54%> (+0.14%)	⬆️
py3.11	75.22% <79.54%> (+0.14%)	⬆️
py3.12	75.23% <79.54%> (+0.14%)	⬆️
py3.13	75.22% <79.54%> (+0.14%)	⬆️
py3.14	76.16% <79.54%> (+0.15%)	⬆️
unit	64.06% <79.54%> (+0.13%)	⬆️

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

Files with missing lines	Coverage Δ
sqlspec/builder/_base.py	74.14% <100.00%> (-0.86%)	⬇️
sqlspec/builder/_column.py	76.34% <100.00%> (+1.61%)	⬆️
sqlspec/builder/_merge.py	82.83% <100.00%> (ø)
sqlspec/builder/_join.py	69.07% <80.00%> (+1.75%)	⬆️
sqlspec/builder/_ddl.py	65.53% <82.14%> (+2.70%)	⬆️
sqlspec/builder/_parsing_utils.py	72.82% <70.96%> (+6.15%)	⬆️
sqlspec/builder/_select.py	63.49% <52.63%> (+1.25%)	⬆️
sqlspec/builder/_factory.py	81.83% <85.88%> (+8.16%)	⬆️

... and 5 files with indirect coverage changes

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