SCIX-818 feat(AbstractSources): add access-level badges to full text sources

[thostetler]

Full text sources previously relied on icon color alone (green vs gray)
to indicate access level, making it difficult to scan at a glance.

• Add "Available" / "Login required" pill badges next to each source group name in accordion view
• Add per-item access tags in the dropdown menu view
• Extract access label derivation into accessLabel.ts helper
• Normalize institution icon sizing and style it as subtle dark gray
• Add unit and integration tests for access label logic and badge rendering

[codecov]

Codecov Report

❌ Patch coverage is 88.61789% with 14 lines in your changes missing coverage. Please review.
✅ Project coverage is 61.4%. Comparing base (161f125) to head (f5a6348).

Files with missing lines	Patch %	Lines
...components/AbstractSources/AbstractSourceItems.tsx	85.2%	13 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #794     +/-   ##
========================================
+ Coverage    61.3%   61.4%   +0.1%     
========================================
  Files         307     308      +1     
  Lines       35535   35609     +74     
  Branches     1553    1564     +11     
========================================
+ Hits        21762   21836     +74     
+ Misses      13737   13736      -1     
- Partials       36      37      +1     

Files with missing lines	Coverage Δ
src/components/AbstractSources/accessLabel.ts	100.0% <100.0%> (ø)
...components/AbstractSources/AbstractSourceItems.tsx	82.9% <85.2%> (+3.1%)	⬆️

... and 2 files with indirect coverage changes

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[thostetler]

@shinyichen this was in response to a user mentioning that one the desktop view of the site we don't have a clear indication of OPEN_ACCESS links. which is true, in ADS we have text in the popover, but in scix we're only indicating this via color.

Anyway, I thought this was a little better design, but would like some feedback!