feat: añadir sistema de knowledge por agente

Implementa una base de conocimiento persistente por agente siguiendo
el patrón pure core / impure shell:

- pkg/knowledge/: tipos puros (Document, Store interface)
- shell/knowledge/: FileStore con SQLite para indexación y archivos .md
- tools/knowledge.go: 4 tools LLM (search, read, write, list)
- tools/knowledge_test.go: tests unitarios de las tools
- internal/config/schema.go: nuevo KnowledgeToolCfg en ToolsCfg
- agents/runtime.go: inicialización del store y registro de tools
- agents/*/knowledge/about-me.md: documentos semilla para cada agente

Cada agente puede buscar, leer, crear y actualizar documentos de
conocimiento. Los archivos .md viven en agents/<id>/knowledge/ y se
indexan en SQLite (agents/<id>/data/knowledge.db).

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

agents/runtime.go

@@ -21,6 +21,7 @@ import (
 	"github.com/enmanuel/agents/pkg/personality"
 	"github.com/enmanuel/agents/shell/bus"
 	"github.com/enmanuel/agents/shell/effects"
+	shellknowledge "github.com/enmanuel/agents/shell/knowledge"
 	shelllm "github.com/enmanuel/agents/shell/llm"
 	"github.com/enmanuel/agents/shell/matrix"
 	shellmem "github.com/enmanuel/agents/shell/memory"
@@ -53,6 +54,9 @@ type Agent struct {
 	windowSize int
 	roomCtx    *tools.RoomContext
 
+	// Knowledge store — non-nil when knowledge is enabled
+	knowledgeStore *shellknowledge.FileStore
+
 	// Bus — set via SetBus() when running under the unified launcher
 	agentBus *bus.Bus
 }
@@ -159,8 +163,27 @@ func New(cfg *config.AgentConfig, rules []decision.Rule, logger *slog.Logger) (*
 		logger.Info("memory enabled", "window_size", windowSize, "db", dbPath)
 	}
 
+	// Knowledge store
+	var kStore *shellknowledge.FileStore
+	if cfg.Tools.Knowledge.Enabled {
+		knowledgeDir := cfg.Tools.Knowledge.Dir
+		if knowledgeDir == "" {
+			knowledgeDir = filepath.Join("agents", cfg.Agent.ID, "knowledge")
+		}
+		knowledgeDBPath := filepath.Join("agents", cfg.Agent.ID, "data", "knowledge.db")
+		var kErr error
+		kStore, kErr = shellknowledge.New(knowledgeDir, knowledgeDBPath, logger)
+		if kErr != nil {
+			logger.Error("knowledge_store_init_failed", "err", kErr)
+		} else {
+			if syncErr := kStore.Sync(context.Background()); syncErr != nil {
+				logger.Error("knowledge_sync_failed", "err", syncErr)
+			}
+		}
+	}
+
 	// Tool registry — register tools enabled in config
-	toolReg := buildToolRegistry(cfg, sshExec, matrixClient, memStore, roomCtx, logger)
+	toolReg := buildToolRegistry(cfg, sshExec, matrixClient, memStore, kStore, roomCtx, logger)
 
 	a := &Agent{
 		cfg:         cfg,
@@ -171,10 +194,11 @@ func New(cfg *config.AgentConfig, rules []decision.Rule, logger *slog.Logger) (*
 		toolReg:     toolReg,
 		logger:      logger,
 		cryptoStore: cryptoStore,
-		windows:     make(map[string]memory.Window),
-		memStore:    memStore,
-		windowSize:  windowSize,
-		roomCtx:     roomCtx,
+		windows:        make(map[string]memory.Window),
+		memStore:       memStore,
+		knowledgeStore: kStore,
+		windowSize:     windowSize,
+		roomCtx:        roomCtx,
 	}
 
 	// Register memory_clear_context with self as WindowClearer (after a is created)
@@ -217,6 +241,9 @@ func (a *Agent) Run(ctx context.Context) error {
 	if a.memStore != nil {
 		defer a.memStore.Close()
 	}
+	if a.knowledgeStore != nil {
+		defer a.knowledgeStore.Close()
+	}
 	a.logger.Info("agent starting",
 		"id", a.cfg.Agent.ID,
 		"name", a.cfg.Agent.Name,
@@ -605,6 +632,7 @@ func buildToolRegistry(
 	sshExec *ssh.Executor,
 	matrixClient *matrix.Client,
 	memStore memory.Store,
+	kStore *shellknowledge.FileStore,
 	roomCtx *tools.RoomContext,
 	logger *slog.Logger,
 ) *tools.Registry {
@@ -643,5 +671,14 @@ func buildToolRegistry(
 		logger.Debug("registered memory tools")
 	}
 
+	// Knowledge tools
+	if cfg.Tools.Knowledge.Enabled && kStore != nil {
+		reg.Register(tools.NewKnowledgeSearch(kStore))
+		reg.Register(tools.NewKnowledgeRead(kStore))
+		reg.Register(tools.NewKnowledgeWrite(kStore))
+		reg.Register(tools.NewKnowledgeList(kStore))
+		logger.Debug("registered knowledge tools")
+	}
+
 	return reg
 }