feat: add window function support

[KKould]

What problem does this PR solve?

KiteSQL cannot currently bind or execute SQL window functions, so queries that need ranking or partition-level aggregate results are rejected.

Issue link: N/A

What is changed and how it works?

• Adds binding, logical and physical planning, optimization, execution, and serialization for window functions.
• Supports ROW_NUMBER, RANK, DENSE_RANK, and COUNT/SUM/AVG/MIN/MAX with OVER.
• Separates window functions from their partition and ordering specification. Functions sharing a specification use one Window operator; different specifications produce separate Sort and Window layers.
• Reuses the existing Sort executor for window ordering and aggregate accumulators for aggregate window functions.
• Buffers and reuses only the current partition during execution.
• Adds explicit ORM APIs for the supported window functions.
• Rejects explicit frames, named windows, and QUALIFY as unsupported instead of silently accepting them.

Code changes

• Has Rust code change
• Has CI related scripts change

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

The coverage includes ranking and aggregate functions, peer rows, null values, shared and different window specifications, duplicate calls, grouped aggregates feeding windows, View round trips, unsupported syntax, and Explain plans.

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Note for reviewer

Window functions with the same specification are evaluated together. A change in PARTITION BY or window ORDER BY creates another Sort and Window layer.

[codecov]

Codecov Report

❌ Patch coverage is 95.79390% with 40 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.84%. Comparing base (362157d) to head (692aef6).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/binder/parser.rs	93.47%	6 Missing ⚠️
src/binder/window.rs	96.10%	6 Missing ⚠️
src/planner/mod.rs	0.00%	6 Missing ⚠️
src/expression/window.rs	77.77%	4 Missing ⚠️
src/planner/operator/window.rs	84.61%	4 Missing ⚠️
src/expression/evaluator.rs	0.00%	3 Missing ⚠️
src/expression/mod.rs	95.52%	3 Missing ⚠️
src/execution/dql/window/function.rs	97.22%	2 Missing ⚠️
src/binder/aggregate.rs	95.00%	1 Missing ⚠️
src/binder/select.rs	95.00%	1 Missing ⚠️
... and 4 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #375      +/-   ##
==========================================
+ Coverage   92.74%   92.84%   +0.10%     
==========================================
  Files         243      249       +6     
  Lines       41025    41790     +765     
==========================================
+ Hits        38049    38802     +753     
- Misses       2976     2988      +12     

Flag	Coverage Δ
rust	92.84% <95.79%> (+0.10%)	⬆️

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

Files with missing lines	Coverage Δ
src/binder/expr.rs	94.42% <100.00%> (-0.21%)	⬇️
src/binder/mod.rs	85.52% <ø> (ø)
src/db.rs	92.90% <100.00%> (+<0.01%)	⬆️
src/execution/dql/aggregate/hash_agg.rs	95.36% <100.00%> (+0.03%)	⬆️
src/execution/dql/aggregate/min_max.rs	96.29% <100.00%> (+5.82%)	⬆️
src/execution/dql/aggregate/simple_agg.rs	89.58% <100.00%> (+0.22%)	⬆️
src/execution/dql/aggregate/sum.rs	100.00% <100.00%> (+23.52%)	⬆️
src/execution/dql/mod.rs	100.00% <ø> (ø)
src/execution/dql/window.rs	100.00% <100.00%> (ø)
src/execution/mod.rs	95.09% <100.00%> (+0.05%)	⬆️
... and 26 more

... and 1 file with indirect coverage changes

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