refactor: rebrand from cs-agent to BossChat

- Rename Go module: cs-agent → bosschat
- Rename all import paths across 200+ Go files
- Rename SDK: cs-ai-agent-sdk → bosschat-sdk
- Rename message protocol: cs-agent:* → bosschat:*
- Rename JS globals: CSAgentConfig → BossChatConfig
- Rename CSS classes: cs-agent-* → bosschat-*
- Update Makefile APP_NAME and ARCHIVE_NAME
- Update logo assets
- Fix display name: BoosChat → BossChat

internal/ai/runtime/instruction/helpers.go

@@ -5,9 +5,9 @@ import (
 	"fmt"
 	"strings"
 
-	runtimetooling "cs-agent/internal/ai/runtime/tooling"
-	"cs-agent/internal/models"
-	"cs-agent/internal/pkg/toolx"
+	runtimetooling "bosschat/internal/ai/runtime/tooling"
+	"bosschat/internal/models"
+	"bosschat/internal/pkg/toolx"
 )
 
 func BuildSelectedSkillActivationInstruction(skill *models.SkillDefinition) string {

internal/ai/runtime/instruction/providers.go

@@ -1,9 +1,9 @@
 package instruction
 
 import (
-	"cs-agent/internal/ai/runtime/tooling"
-	"cs-agent/internal/models"
-	"cs-agent/internal/pkg/toolx"
+	"bosschat/internal/ai/runtime/tooling"
+	"bosschat/internal/models"
+	"bosschat/internal/pkg/toolx"
 )
 
 type ToolAppendixProvider struct{}

internal/ai/runtime/instruction/service.go

@@ -3,8 +3,8 @@ package instruction
 import (
 	"strings"
 
-	runtimetooling "cs-agent/internal/ai/runtime/tooling"
-	"cs-agent/internal/models"
+	runtimetooling "bosschat/internal/ai/runtime/tooling"
+	"bosschat/internal/models"
 )
 
 type Service struct {