Move schema discovery message to sidebar alert

[kmcginnes]

Description

Move the implicit schema discovery message from a tooltip in the Schema Graph toolbar to an Alert component at the bottom of the sidebar detail panels. This makes the message more visible and contextually relevant when viewing node or edge details.

• Remove the InfoTooltip from the Schema Graph toolbar title for a cleaner header
• Add a SchemaDiscoveryAlert component that uses the existing Alert pattern to inform users the schema was implicitly discovered
• Place SchemaDiscoveryAlert at the bottom of NodeLabelDetails and EdgeConnectionDetails sidebars
• Remove per-section description text (DetailsDescription) to reduce visual noise
• Add "small" size variant and "subtle" icon variant to EmptyState for compact empty states in the sidebar
• Tighten vertical spacing in Details sections (space-y-5 → space-y-3)

Validation

• Open the Schema Graph view
• Select a node label or edge connection in the sidebar
• Verify the "Schema Discovery" alert appears at the bottom of the detail panel
• Verify the toolbar title no longer has a tooltip icon
• Verify empty property states render with the smaller, subtle icon style

Node Label Details	Edge Label Details (with no properties)

Related Issues

• Resolves Update schema view sidebar messaging to clarify implicit schema discovery #1544

Check List

• I confirm that my contribution is made under the terms of the Apache 2.0
  license.
• I have run pnpm checks to ensure code compiles and meets standards.
• I have run pnpm test to check if all tests are passing.
• I have covered new added functionality with unit tests if necessary.
• I have added an entry in the Changelog.md.

[codecov]

Codecov Report

❌ Patch coverage is 41.66667% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.75%. Comparing base (c5affc5) to head (c9f6132).
⚠️ Report is 85 commits behind head on main.

Files with missing lines	Patch %	Lines
...dules/SchemaGraph/Sidebar/SchemaDiscoveryAlert.tsx	0.00%	2 Missing and 1 partial ⚠️
...kages/graph-explorer/src/components/EmptyState.tsx	50.00%	1 Missing ⚠️
...rer/src/modules/SchemaGraph/SchemaGraphToolbar.tsx	0.00%	0 Missing and 1 partial ⚠️
...ules/SchemaGraph/Sidebar/EdgeConnectionDetails.tsx	0.00%	0 Missing and 1 partial ⚠️
...c/modules/SchemaGraph/Sidebar/NodeLabelDetails.tsx	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1553       +/-   ##
===========================================
+ Coverage   47.81%   64.75%   +16.93%     
===========================================
  Files         382      366       -16     
  Lines        8525     8287      -238     
  Branches     3159     3093       -66     
===========================================
+ Hits         4076     5366     +1290     
+ Misses       3070     2074      -996     
+ Partials     1379      847      -532     

Flag	Coverage Δ
unittests	64.75% <41.66%> (+16.93%)	⬆️

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