Add run-button uv-mode test coverage

[Copilot]

• The run button/task execution now uses uv run --python ... when python-envs.alwaysUseUv applies.
• The uv setting is resolved with project scope so workspace-folder precedence is respected.
• Updated the setting description to mention run-button behavior.
• Added unit tests for uv, quoted-uv, and non-uv paths.

[Copilot]

Pull request overview

This PR adds UV-mode coverage for run-button task execution, ensuring that when python-envs.alwaysUseUv applies the task is executed via uv run --python <interpreter> ..., and that the setting is resolved with proper project/workspace scope precedence.

Changes:

• Updated runAsTask() to route task execution through uv run --python ... when shouldUseUv() applies (including passing project URI scope for settings precedence).
• Extended shouldUseUv() to accept an optional VS Code configuration scope for correct workspace-folder precedence.
• Added/expanded unit tests covering UV/non-UV execution paths, quoting behavior for the UV executable, and scope passing.

Show a summary per file

File	Description
src/test/features/execution/runAsTask.unit.test.ts	Adds unit test coverage for UV-mode task invocation, scope passing, and argument ordering.
src/managers/builtin/helpers.ts	Extends shouldUseUv() with an optional ConfigurationScope to respect settings precedence.
src/features/execution/runAsTask.ts	Implements UV-mode task execution (uv run --python ...) and passes project URI scope to shouldUseUv().
package.nls.json	Updates the alwaysUseUv setting description to mention run-button behavior.

Copilot's findings

• Files reviewed: 4/4 changed files
• Comments generated: 2

[eleanorjboyd]

this PR needs to updated to better respect PEP 723 style scripts:

Run Button: Interpreter Selection Logic
When a user clicks Run on a Python script, the behavior depends on whether the script uses PEP 723 inline metadata:

PEP 723 script (/// script block present): Run with uv run <script> and let uv manage interpreter and dependency resolution entirely. The script is self-contained and declares its own requirements, so the user's saved interpreter is not relevant.
Standard script (no /// script block): Run with uv run --python <saved_interpreter> <script>, using the interpreter the user has configured for the project/workspace.

Detection is done by scanning the script file for the /// script marker before constructing the run command.