Summary

• Pre-warm conversation workers on SendBox input focus with 1s debounce, reducing ACP first-token latency by ~7s for existing conversations
• Suppress ACP stream events during warmup to prevent sidebar loading spinner
• Add warmup trigger after new conversation creation in GuidPage

Changes

IPC Layer

• Add conversation.warmup IPC channel (ipcBridge.ts)
• Add warmup provider: calls getOrBuildTask for all agents, plus initAgent() for ACP (conversationBridge.ts)

ACP Agent

• Add bootstrapping flag to suppress onStreamEvent during warmup, preventing sidebar loading spinner
• Clear bootstrapping on sendMessage() so progress events show during actual user waits
• Remove temporary [Send-PERF] logging (AcpAgentManager.ts)

Renderer

• Trigger warmup on SendBox focus with 1s debounce; cancel on blur to avoid rapid switching spawning multiple CLI processes (sendbox.tsx)
• Trigger warmup after new conversation creation in all 4 agent paths: gemini, openclaw, nanobot, acp (useGuidSend.ts)

Tests

• Add 4 warmup provider tests: getOrBuildTask call, ACP initAgent dispatch, non-ACP skip, error suppression (conversationBridge.test.ts)
• Add 4 SendBox warmup debounce tests: 1s trigger, blur cancel, same-conversation dedup, different-conversation re-trigger (sendboxWarmup.dom.test.ts)

Related Issue

Closes #1701

Test Plan

• Open an existing ACP conversation → verify no sidebar loading spinner on entry
• Focus input, wait 1s, then send message → verify faster first response (~4s API only vs ~11s without warmup)
• Rapidly switch between conversations → verify only the final conversation triggers warmup
• Create a new conversation from GuidPage → verify warmup triggers before navigation
• bun run test passes (13 tests in warmup-related files)