refactor(agent): Agent Looper refactor phase2, restructure pipeline and rename loop files to agent (#2585)

* refactor(agent): introduce interfaces for MessageBus and ChannelManager

Phase 2 of loop.go refactor — dependency inversion using adapter pattern.

- Add interfaces.MessageBus and interfaces.ChannelManager interfaces
- Create adapters/messagebus.go wrapping *bus.MessageBus
- Create adapters/channelmanager.go wrapping *channels.Manager
- Update AgentLoop to use interfaces instead of concrete types
- Update registerSharedTools to accept interfaces.MessageBus

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* refactor(agent): restructure pipeline and rename loop files

Pipeline refactoring:
- Split pipeline.go (1400 lines) into focused files:
  - pipeline_setup.go (~115 lines): SetupTurn method
  - pipeline_llm.go (~519 lines): CallLLM method
  - pipeline_execute.go (~693 lines): ExecuteTools method
  - pipeline_finalize.go (~78 lines): Finalize method
- Pipeline struct and NewPipeline remain in pipeline.go (~39 lines)

Agent file renaming:
- Rename loop_*.go to agent_*.go for consistent naming:
  - loop.go -> agent.go, loop_message.go -> agent_message.go, etc.
- Merge turn.go + turn_exec.go into turn_state.go
- Rename loop_turn.go -> turn_coord.go

Documentation:
- Update docs/pipeline-restructuring-plan.md
- Add docs/agent-rename-plan.md

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* fix(agent): code format  fixed

* refactor(agent): code test file added/renamed

* docs(agent): update agent refactor docs

* fix(agent): fix agent hardAbortX

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

pkg/agent/interfaces/interfaces.go

@@ -0,0 +1,47 @@
+// PicoClaw - Ultra-lightweight personal AI agent
+
+package interfaces
+
+import (
+	"context"
+
+	"github.com/sipeed/picoclaw/pkg/bus"
+	"github.com/sipeed/picoclaw/pkg/channels"
+)
+
+// MessageBus publishes inbound and outbound messages.
+// It is the primary communication channel for the agent loop.
+type MessageBus interface {
+	// PublishInbound sends an inbound message to be processed.
+	PublishInbound(ctx context.Context, msg bus.InboundMessage) error
+
+	// PublishOutbound sends an outbound message to the appropriate channel.
+	PublishOutbound(ctx context.Context, msg bus.OutboundMessage) error
+
+	// PublishOutboundMedia sends an outbound media message.
+	PublishOutboundMedia(ctx context.Context, msg bus.OutboundMediaMessage) error
+
+	// InboundChan returns the channel for receiving inbound messages.
+	InboundChan() <-chan bus.InboundMessage
+}
+
+// ChannelManager manages channel lifecycle and provides channel access.
+type ChannelManager interface {
+	// GetChannel returns the channel with the given name.
+	GetChannel(name string) (channels.Channel, bool)
+
+	// GetEnabledChannels returns the list of enabled channel names.
+	GetEnabledChannels() []string
+
+	// InvokeTypingStop signals that typing has stopped.
+	InvokeTypingStop(channel, chatID string)
+
+	// SendMessage sends a text message to the specified channel and chat.
+	SendMessage(ctx context.Context, msg bus.OutboundMessage) error
+
+	// SendMedia sends a media message to the specified channel and chat.
+	SendMedia(ctx context.Context, msg bus.OutboundMediaMessage) error
+
+	// SendPlaceholder sends a placeholder message (e.g., for audio transcription).
+	SendPlaceholder(ctx context.Context, channel, chatID string) bool
+}