feat: View XML button & view XML as new tab

[vochaparro2]

PULL REQUEST

PR title: Remember to name your PR descriptively and follow conventional commits!

Summary

• Adds a "View XML" button to the eCR viewer page that toggles in-place between the eCR summary and the raw eICR/RR XML, displayed in a collapsible, line-numbered viewer.
• Adds a new API - GET /api/view-xml?id= — retrieves the stored XML zip from S3 and returns { ecrXml, rrXml } as JSON. Returns 404 if XML storage is disabled or the archive is missing
• The "View XML" button is hidden when SAVE_XML is not set.
• Uses react-xml-viewer with collapsible nodes and line numbers.
• Fixed an issue that prevented RR files from being saved correctly to blob storage.

Related Issue

Fixes #1091

Acceptance Criteria

When there are eICR and RR XMLs:

Individual eCR

• "View XML" button in the eCR

XML tab
Only show tabs for files that exist. For example, if there is an eICR but no RR, only show a eICR tab.
When the user selects "View XML", they will be taken to a side menu that includes:

• Tab for eICR XML
• Tab for RR XML

When there no eICR or RR XMLs:

• Do not show the "View XML" button

Additional Information

Anything else the review team should know?

Checklist

• If this code affects the other scrum team, have they been notified? (In Slack, as reviewers, etc.)

[codecov-commenter]

Codecov Report

❌ Patch coverage is 70.96774% with 27 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.79%. Comparing base (51bea25) to head (28db258).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...-viewer/src/app/view-data/components/XmlViewer.tsx	48.07%	27 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1506      +/-   ##
==========================================
+ Coverage   85.91%   89.79%   +3.88%     
==========================================
  Files         259      183      -76     
  Lines       11710     7049    -4661     
  Branches     1356     1388      +32     
==========================================
- Hits        10061     6330    -3731     
+ Misses       1642      712     -930     
  Partials        7        7              

Flag	Coverage Δ
ecr-viewer	90.71% <70.96%> (-0.30%)	⬇️
ingestion	?
message-parser	?
orchestration	85.29% <ø> (ø)
trigger-code-reference	?

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