Clean up typos in docs, comments, and UI copy

[PeterDaveHello]

Description of Changes

Fix wording, numbering, path references, and minor grammar issues across project guides, backend comments, and frontend strings.

This keeps documentation and user-facing text consistent without changing application behavior.

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Checklist

General

• I have read the Contribution Guidelines
• I have read the Stirling-PDF Developer Guide (if applicable)
• I have read the How to add new languages to Stirling-PDF (if applicable)
• I have performed a self-review of my own code
• My changes generate no new warnings

Documentation

• I have updated relevant docs on Stirling-PDF's doc repo (if functionality has heavily changed)
• I have read the section Add New Translation Tags (for new translation tags only)

Translations (if applicable)

• I ran scripts/counter_translation.py

UI Changes (if applicable)

• Screenshots or videos demonstrating the UI changes are attached (e.g., as comments or direct attachments in the PR)

Testing (if applicable)

• I have tested my changes locally. Refer to the Testing Guide for more details.

[Copilot]

Pull request overview

This PR cleans up typos and improves consistency in documentation, comments, and user-facing text across the repo.

Changes:

• Fixes wording/grammar issues in multiple markdown guides and template docs.
• Corrects typos in frontend/backend comments and UI error text.
• Updates a few path/script references in documentation to match current repo structure.

Reviewed changes

Copilot reviewed 11 out of 12 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
testing/cucumber/exampleFiles/example.md	Fixes markdown list formatting/typo in example content.
README.md	Cleans up Support section bullet formatting and “GitHub” capitalization.
frontend/src/proprietary/constants/staticStripeLinks.ts	Fixes a typo in a comment (“PRODUCTION”).
frontend/src/core/tests/test-fixtures/README.md	Corrects the documented fixtures directory path.
frontend/src/core/services/googleDrivePickerService.ts	Fixes typo in an error message (token handling path).
frontend/README.md	Minor grammar fix in environment variable guidance.
docs/type3_fallback_plan.md	Updates the referenced PDF download script name in the workflow table.
devGuide/STYLELINT.md	Fixes Stylelint command paths/config reference in docs.
devGuide/DeveloperGuide.md	Minor wording/grammar fixes in build notes.
DeveloperGuide.md	Fixes numbering and wording/grammar in setup/build notes.
app/proprietary/src/main/resources/templates/AUDIT_USAGE.md	Grammar fix in audit event description.
app/common/src/main/java/stirling/software/common/configuration/AppConfig.java	Comment wording fix (“use case”).

Comments suppressed due to low confidence (1)

frontend/src/core/services/googleDrivePickerService.ts:164

• When response.access_token is null, reject(...) is called but execution continues, setting this.accessToken to null and then calling resolve(). Add an early return (or structure with else) after the reject to prevent resolving the promise on an error path.

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