Auto-increment job name when adaptor already used in workflow

[brandonjackson]

Description

This PR fixes duplicate job names when adding multiple jobs with the same adaptor. When adding a new job node with an adaptor that already has a job using the same display name, append an incrementing number to make the name unique (e.g. "Whatsapp" → "Whatsapp 1" → "Whatsapp 2"). This prevents the "Job name should be distinct" save error.

Closes #4464

Validation steps

1. Open a workflow and add a job with e.g. the Whatsapp adaptor
2. Add another job with the same adaptor
3. Verify the second job is named "Whatsapp 1" instead of "Whatsapp"
4. Add a third — verify it's named "Whatsapp 2"

Additional notes for the reviewer

AI Usage

• I have used Claude Code
• I have used another model
• I have not used AI

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• I have performed an AI review of my code (we recommend using /review
  with Claude Code)
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  (e.g., :owner, :admin, :editor, :viewer)
• I have updated the changelog.
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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.45%. Comparing base (b4da2cf) to head (7dde0bf).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4463   +/-   ##
=======================================
  Coverage   89.44%   89.45%           
=======================================
  Files         425      425           
  Lines       20212    20212           
=======================================
+ Hits        18079    18081    +2     
+ Misses       2133     2131    -2     

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[elias-ba]

Nicely done @brandonjackson 👏🏽

[elias-ba]

Hey @brandonjackson, thank you very much for this PR; this is really great! The code is clean and handles edge cases well. I went ahead and tidied up a few things:

• Created an issue (#4464) and linked it to this PR
• Added a changelog entry under [Unreleased] > Fixed
• Updated the PR description to match our PR template. A tip for next time: you can instruct Claude Code to always use the template in .github/ when opening PRs, saves a step!
• Added Taylor as a second reviewer; we have a two-review rule before merging to main

Everything else looks good to go. Thanks again!