feat(gateway): add connector read commands

[aidandaly24]

Summary

• add gateway connector get for connector-backed Gateway Targets
• add gateway connector list by filtering Target summaries with targetType: CONNECTOR
• preserve existing Target read APIs and service pagination tokens

Testing

• bun test src/handlers/gateway/gateway.test.tsx
• bun run build
• focused Prettier and oxlint checks

_{Stack created with GitHub Stacks CLI}

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.14%. Comparing base (d08ecca) to head (dd0fb32).
⚠️ Report is 2 commits behind head on refactor.

Additional details and impacted files

@@             Coverage Diff              @@
##           refactor    #1922      +/-   ##
============================================
+ Coverage     96.12%   96.14%   +0.02%     
============================================
  Files           232      235       +3     
  Lines         11526    11600      +74     
============================================
+ Hits          11079    11153      +74     
  Misses          447      447              

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[jariy17]

Looks good! Left nit comment and unit test question (TDD)