feat: import agents_and_robots platform as unibots (Matrix-out, unibus transport)

Reemplaza el scaffold del echobot por la plataforma completa de bots traida
desde ~/DataProyects/Github/agents_and_robots tras la operacion Matrix-out:
los bots ya no hablan por Matrix sino por el bus unibus (modelo todo-rooms +
E2E via shell/transportunibus sobre github.com/enmanuel/unibus/pkg/client).

- go.mod: replace de unibus -> ../unibus y de fn-registry -> ../../../.. (paths
  relativos reajustados a la nueva ubicacion dentro de fn_registry).
- app.md: bump a 0.2.0, descripcion + arquitectura + comandos + gotchas reales.
- modulo Go conservado como github.com/enmanuel/agents (sin reescribir imports).

agents_and_robots queda archivado como museo de la era Matrix.

pkg/knowledge/store.go

@@ -0,0 +1,25 @@
+package knowledge
+
+import "context"
+
+// Store is the pure interface for knowledge operations.
+// Implemented by shell/knowledge.
+type Store interface {
+	// Search performs full-text search across all documents.
+	Search(ctx context.Context, query string, limit int) ([]SearchResult, error)
+
+	// Get retrieves a document by slug.
+	Get(ctx context.Context, slug string) (*Document, error)
+
+	// Put creates or updates a document (file + index).
+	Put(ctx context.Context, doc Document) error
+
+	// List returns all document slugs with titles.
+	List(ctx context.Context) ([]Document, error)
+
+	// Sync re-indexes all files from disk. Called on startup.
+	Sync(ctx context.Context) error
+
+	// Close releases resources.
+	Close() error
+}

pkg/knowledge/types.go

@@ -0,0 +1,20 @@
+// Package knowledge provides pure types for the agent knowledge base.
+package knowledge
+
+import "time"
+
+// Document represents a knowledge document.
+type Document struct {
+	Slug      string    // filename without extension, e.g. "go-patterns"
+	Title     string    // first H1 line from markdown, or humanized slug
+	Content   string    // full file content
+	UpdatedAt time.Time // file mtime
+}
+
+// SearchResult is a document matched by a search query.
+type SearchResult struct {
+	Slug    string
+	Title   string
+	Snippet string  // relevant fragment with match highlights
+	Rank    float64 // FTS5 relevance score
+}