Content Classification: Dynamicize taxonomy error messages

[Infinite-Null]

What?

This PR updates the error and notice messages in the Content_Classification ability to dynamically display the specific taxonomy label (e.g., "category" or "tag") rather than generic hardcoded "taxonomy" terminology.

Why?

When users interacted with specific taxonomy panels (such as "Suggest Categories" under the Categories sidebar panel), error notices displayed generic phrasing like "No taxonomy suggestions were generated." or "You do not have permission to generate taxonomy suggestions." This caused confusion as users were explicitly generating suggestions for categories.

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Sonnet 4.6
Used for: Validating bug, suggesting a fix.

Testing Instructions

1. Open a Post.
2. Open the Categories accordion panel in the right sidebar.
3. Trigger Category suggestion generation with empty content or under conditions with no results/no permission.
4. Verify the notice banner displays "Content is required to generate category suggestions." or "No category suggestions were generated." (instead of generic "No taxonomy suggestions were generated.").

Screenshots or screencast

Before

Screen.Recording.2026-08-05.at.1.30.25.PM.mov

After

Screen.Recording.2026-08-05.at.1.29.48.PM.mov

Changelog Entry

Fixed - Display specific taxonomy labels (e.g. category) in Content Classification notice error messages instead of generic terminology.

[github-actions]

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Co-authored-by: Infinite-Null <ankitkumarshah@git.wordpress.org>
Co-authored-by: jeffpaul <jeffpaul@git.wordpress.org>
Co-authored-by: dkotter <dkotter@git.wordpress.org>

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[codecov]

Codecov Report

❌ Patch coverage is 89.47368% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.52%. Comparing base (441dcbb) to head (0549deb).

Files with missing lines	Patch %	Lines
.../Content_Classification/Content_Classification.php	89.47%	2 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop     #916      +/-   ##
=============================================
+ Coverage      74.42%   74.52%   +0.10%     
- Complexity      3116     3124       +8     
=============================================
  Files            132      132              
  Lines          12179    12193      +14     
=============================================
+ Hits            9064     9087      +23     
+ Misses          3115     3106       -9     

Flag	Coverage Δ
unit	74.52% <89.47%> (+0.10%)	⬆️

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[jeffpaul]

Tests well on Playground, will await @dkotter's review before merging

[Infinite-Null]

Thanks for the feedback! I’ve reworked the changes. Could you please review the updated changes when you get a chance. Thank you.

cc: @jeffpaul @dkotter