feat(builder): support UPDATE FROM builders and preserve DML CTEs

[cofin]

Adds query-builder and subquery sources to Update.from_() with bound-parameter merging, and preserves explicit CTEs on UPDATE and DELETE through with_cte()/with_(). Dialect checks retain supported UPDATE FROM forms, including BigQuery, and reject unsupported forms with SQLBuilderError, including Spanner PostgreSQL mode.

Adds the parameterized sql.values() factory and Values builder, with CTE bindings retained when queries are composed. Use sql.column("values") for a column with that name. Includes unit/integration regressions, documentation, and v0.63.0 release notes.

Validation: make lint passed during review. Regression tests were added or updated, but no local test suite was run in this review. Hosted CI for the latest branch head is still pending.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 90.97473% with 25 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.91%. Comparing base (1e36450) to head (17a6f2e).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
sqlspec/builder/_base.py	85.36%	3 Missing and 9 partials ⚠️
sqlspec/builder/_dml.py	87.23%	0 Missing and 6 partials ⚠️
sqlspec/builder/_values.py	95.38%	1 Missing and 5 partials ⚠️
sqlspec/builder/_select.py	88.88%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #779      +/-   ##
==========================================
+ Coverage   77.49%   78.91%   +1.41%     
==========================================
  Files         489      491       +2     
  Lines       72169    72437     +268     
  Branches    10128    10181      +53     
==========================================
+ Hits        55930    57163    +1233     
+ Misses      13050    11767    -1283     
- Partials     3189     3507     +318     

Flag	Coverage Δ
integration	62.38% <45.12%> (+3.48%)	⬆️
py3.10	77.06% <90.97%> (+0.56%)	⬆️
py3.11	77.05% <90.97%> (+10.36%)	⬆️
py3.12	77.06% <90.97%> (+0.55%)	⬆️
py3.13	77.06% <90.97%> (+10.37%)	⬆️
py3.14	78.18% <90.94%> (+11.95%)	⬆️
unit	67.21% <90.97%> (+0.18%)	⬆️

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Files with missing lines	Coverage Δ
sqlspec/builder/__init__.py	100.00% <100.00%> (ø)
sqlspec/builder/_factory.py	85.30% <100.00%> (+0.88%)	⬆️
sqlspec/data_dictionary/_types.py	92.41% <100.00%> (-0.17%)	⬇️
...qlspec/data_dictionary/dialects/bigquery/config.py	100.00% <ø> (ø)
...pec/data_dictionary/dialects/cockroachdb/config.py	100.00% <ø> (ø)
sqlspec/data_dictionary/dialects/duckdb/config.py	100.00% <ø> (ø)
sqlspec/data_dictionary/dialects/mssql/config.py	65.79% <ø> (-6.32%)	⬇️
sqlspec/data_dictionary/dialects/mysql/config.py	80.68% <ø> (-7.96%)	⬇️
sqlspec/data_dictionary/dialects/oracle/config.py	82.85% <100.00%> (-5.38%)	⬇️
...qlspec/data_dictionary/dialects/postgres/config.py	100.00% <ø> (ø)
... and 6 more

... and 70 files with indirect coverage changes

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