Merge upstream/main into bugfix/fix-duplicate-telegram-messages.
Conflict resolutions:
- pkg/agent/loop.go: Adopt upstream's processSystemMessage which removes
runAgentLoop call entirely (subagents now communicate via message tool
directly). Keep PR's HasSentInRound() check in Run() for normal
message processing path.
- pkg/tools/message.go: Merge both changes - keep sentInRound tracking
from PR and adopt upstream's *ToolResult return type with Silent: true.