feat(workflow-operator): add Python UDF UI parameter injection model

[carloea2]

What changes were proposed in this PR?

This PR adds the Scala backend foundation for Python UDF UI parameters.

It introduces:

Area	Change
UI parameter model	Adds UiUDFParameter, containing backend-compatible attribute metadata and an editable value.
Python UDF injector	Adds PythonUdfUiParameterInjector, which validates UI parameters and injects a reserved hook method into supported Python UDF classes.
Safe string encoding	Marks Attribute.getName() as encodable so UI parameter names are safely rendered through the Python template builder.
Test coverage	Adds Scala tests for hook injection, validation, unsupported types, reserved method conflicts, and unchanged behavior when no UI parameters exist.

This PR is stacked after the merged frontend foundation PR #5043. It does not yet wire the injector into operator execution; that wiring is handled by later PRs in the stack.

Existing Python UDF workflow execution remains unchanged in this PR because PythonUDFOpDescV2, PythonUDFSourceOpDescV2, and DualInputPortsPythonUDFOpDescV2 are not modified here.

Any related issues, documentation, discussions?

Part of the Python UDF UI parameter feature split from feat/ui-parameter.

Related tracking issue / stack: #5044

Stack order:

1. Frontend UI parameter building blocks: feat(frontend): add Python UDF UI parameter form support #5043
2. Scala backend injection model: this PR
3. Python runtime support
4. End-to-end integration

How was this PR tested?

Commands run:

sbt "WorkflowOperator / Test / testOnly org.apache.texera.amber.operator.udf.python.PythonUdfUiParameterInjectorSpec"
sbt scalafmtAll
sbt scalafmtCheckAll "scalafixAll --check"

Results:

• PythonUdfUiParameterInjectorSpec: 10 tests passed.
• scalafmtAll: no file changes.
• scalafmtCheckAll and scalafixAll --check: passed.

Was this PR authored or co-authored using generative AI tooling?

No

[codecov-commenter]

Codecov Report

❌ Patch coverage is 90.36145% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 43.44%. Comparing base (e4557ee) to head (4652aac).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ator/udf/python/PythonUdfUiParameterInjector.scala	90.00%	0 Missing and 8 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #5141      +/-   ##
============================================
+ Coverage     43.34%   43.44%   +0.10%     
- Complexity     2213     2215       +2     
============================================
  Files          1049     1051       +2     
  Lines         40561    40644      +83     
  Branches       4322     4335      +13     
============================================
+ Hits          17581    17658      +77     
  Misses        21888    21888              
- Partials       1092     1098       +6     

Flag	Coverage Δ		*Carryforward flag
access-control-service	39.53% <ø> (ø)
agent-service	33.72% <ø> (ø)		Carriedforward from f386522
amber	44.06% <90.36%> (+0.25%)	⬆️
computing-unit-managing-service	0.00% <ø> (ø)
config-service	0.00% <ø> (ø)
file-service	32.18% <ø> (ø)
frontend	34.61% <ø> (ø)		Carriedforward from f386522
python	90.50% <ø> (ø)		Carriedforward from f386522
workflow-compiling-service	56.81% <ø> (ø)

*This pull request uses carry forward flags. Click here to find out more.

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