Fix Kiro ACP stop and icon polish

[declancowen]

Summary

• preserve provider-owned ACP request IDs and permission option IDs for Kiro tool approvals
• keep Kiro active-prompt steering on _message/send while making Stop close the Kiro ACP session when session/cancel is unsupported
• refresh app icon assets with a more macOS-style rounded boundary and keep sidebar/send icon polish

Validation

• bun --filter t3 test src/provider/acp/AcpRuntimeModel.test.ts src/provider/acp/AcpAdapterSupport.test.ts src/provider/acp/StandardAcpAdapter.test.ts
• bun --filter effect-acp test src/client.test.ts src/protocol.test.ts
• bun --filter @t3tools/web test src/components/Sidebar.logic.test.ts src/components/chat/ComposerPrimaryActions.test.ts src/components/ui/sidebar.test.tsx
• bun fmt
• bun lint
• bun typecheck
• git diff --check
• bun run dist:desktop:dmg:arm64

[declancowen]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Keep them coming!

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