chore(pve, v1.2): hard-disable the Python Virtual Environment UI

[xuang7]

What changes were proposed in this PR?

This PR hard-disables the PVE UI behind a single constant (PVE_ENABLED = false in app-setting.ts) so the feature can be restored with a one-line flip:

• The "Python Environment" icon on computing unit rows is hidden, which removes the only entry to the PVE install modal.
• The Python UDF operator's defaultEnv / envName fields are hidden and defaultEnv is forced to true when the property panel opens, so every Python UDF runs on the default environment and the frontend no longer issues any /api/pve request.

The backend (PveResource, PveManager, routing) is untouched and stays dormant.

Before	After

Any related issues, documentation, discussions?

Related to #6131 and #5963.

How was this PR tested?

Existing auto tests passed.

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

Generated-by: Claude Code (Claude Fable 5)

[github-actions]

Automated Reviewer Suggestions

Based on the git blame history of the changed files, we recommend the following reviewers:

• Contributors with relevant context: @SarahAsad23, @aglinxinyuan
  You can notify them by mentioning @SarahAsad23, @aglinxinyuan in a comment.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 28.57143% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 52.32%. Comparing base (b5b0376) to head (eb182c9).
⚠️ Report is 2 commits behind head on release/v1.2.

Files with missing lines	Patch %	Lines
...it-frame/operator-property-edit-frame.component.ts	10.00%	6 Missing and 3 partials ⚠️
...wer-button/computing-unit-selection.component.html	0.00%	1 Missing ⚠️

Additional details and impacted files

@@                Coverage Diff                 @@
##             release/v1.2    #6364      +/-   ##
==================================================
- Coverage           52.32%   52.32%   -0.01%     
  Complexity           2491     2491              
==================================================
  Files                1074     1074              
  Lines               42121    42133      +12     
  Branches             4535     4538       +3     
==================================================
+ Hits                22041    22046       +5     
- Misses              18779    18785       +6     
- Partials             1301     1302       +1     

Flag	Coverage Δ		*Carryforward flag
access-control-service	64.61% <ø> (ø)		Carriedforward from b5b0376
agent-service	34.36% <ø> (ø)		Carriedforward from b5b0376
amber	52.50% <ø> (ø)		Carriedforward from b5b0376
computing-unit-managing-service	1.65% <ø> (ø)		Carriedforward from b5b0376
config-service	56.06% <ø> (ø)		Carriedforward from b5b0376
file-service	58.59% <ø> (ø)		Carriedforward from b5b0376
frontend	47.10% <28.57%> (-0.01%)	⬇️
pyamber	90.81% <ø> (ø)		Carriedforward from b5b0376
python	90.74% <ø> (ø)		Carriedforward from b5b0376
workflow-compiling-service	58.69% <ø> (ø)		Carriedforward from b5b0376

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

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[aglinxinyuan]

LGTM as a temporary solution. Please provide a before-and-after screenshot.

[xuang7]

LGTM as a temporary solution. Please provide a before-and-after screenshot.

Sounds good! I have updated the PR description with screenshots.