refactor(instruction): remove project instruction handling and related tests

internal/ai/runtime/instruction/providers.go

@@ -1,8 +1,6 @@
 package instruction
 
 import (
-	"os"
-	"path/filepath"
 	"strings"
 
 	runtimetooling "cs-agent/internal/ai/runtime/tooling"
@@ -10,56 +8,6 @@ import (
 	"cs-agent/internal/pkg/toolx"
 )
 
-type ProjectInstructionProvider struct {
-	fileName string
-}
-
-func NewProjectInstructionProvider() *ProjectInstructionProvider {
-	return &ProjectInstructionProvider{fileName: "AGENTS.md"}
-}
-
-func (p *ProjectInstructionProvider) Resolve() string {
-	if text := p.loadFromFile(); text != "" {
-		return text
-	}
-	return strings.TrimSpace(DefaultProjectInstruction)
-}
-
-func (p *ProjectInstructionProvider) loadFromFile() string {
-	path := p.resolvePath()
-	if path == "" {
-		return ""
-	}
-	data, err := os.ReadFile(path)
-	if err != nil {
-		return ""
-	}
-	return strings.TrimSpace(string(data))
-}
-
-func (p *ProjectInstructionProvider) resolvePath() string {
-	fileName := "AGENTS.md"
-	if p != nil && strings.TrimSpace(p.fileName) != "" {
-		fileName = strings.TrimSpace(p.fileName)
-	}
-	wd, err := os.Getwd()
-	if err != nil {
-		return ""
-	}
-	dir := wd
-	for {
-		candidate := filepath.Join(dir, fileName)
-		if stat, statErr := os.Stat(candidate); statErr == nil && !stat.IsDir() {
-			return candidate
-		}
-		parent := filepath.Dir(dir)
-		if parent == dir {
-			return ""
-		}
-		dir = parent
-	}
-}
-
 type ToolAppendixProvider struct{}
 
 func NewToolAppendixProvider() *ToolAppendixProvider {