feat(gateway): add interactive invoke console

[aidandaly24]

Summary

• add a persistent POST JSON console for agentcore gateway invoke
• add Gateway switching, raw path editing, generated/continued sessions, and live response streaming
• preserve the headless Gateway invoke contract while allowing CLI flags to seed interactive context
• share the multiline editor with Runtime and keep long payloads within stable terminal rows

UX

• Ctrl+T switches Gateway and clears Gateway-specific state
• Ctrl+P edits the Gateway-relative path; blank uses the exact Gateway URL
• Ctrl+V toggles completed JSON between raw and pretty forms
• CUSTOM_JWT Gateways proactively require a CLI-provided bearer token
• Runtime and MCP session metadata continues across requests

Verification

• 206 pass, 0 fail focused Gateway/Runtime invoke tests
• 1197 pass, 0 fail full bun test src
• bun run typecheck
• bun run lint:check
• bun run format:check
• bun run build
• live TUI validation: NONE, AWS_IAM, CUSTOM_JWT, AUTHENTICATE_ONLY, JWT passthrough, OAuth 3LO, OAuth OBO, inference, Runtime HTTP, MCP aggregation, Lambda, and real SSE streaming

Stack

Depends on #1967. Review this PR against feat/gateway-invoke.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 98.27586% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.98%. Comparing base (4d183dc) to head (e14e884).

Files with missing lines	Patch %	Lines
src/handlers/gateway/invoke/screen.tsx	97.80%	10 Missing ⚠️
src/handlers/gateway/invoke/index.tsx	98.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##           refactor    #1978      +/-   ##
============================================
+ Coverage     96.96%   96.98%   +0.02%     
============================================
  Files           364      366       +2     
  Lines         20758    21304     +546     
============================================
+ Hits          20127    20662     +535     
- Misses          631      642      +11     

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[nborges-aws]

I think we need the same statusCode !== 204 && statusCode !== 205 clause here that we did in the headless invoke PR

[aidandaly24]

Good catch. Fixed in e14e8848 by exempting HTTP 204 and 205 from the TUI binary/unknown-content guard, matching the headless invoke behavior. I also added screen coverage for both statuses with an empty content type and body; the focused Gateway invoke screen suite passes 31/31.

[nborges-aws]

LGTM