refactor(infra): split de drivers pesados a subpaquetes + fix TestSSEHandler

Mueve duckdb_open, clickhouse_open, postgres_open, matrix_* y keyring_token_store
del paquete monolitico functions/infra a subpaquetes propios
(functions/infra/{duckdb,clickhouse,postgres,matrix,keyring}). El paquete infra ya
no importa los drivers (go-duckdb, clickhouse-go, pgx, mautrix, go-keyring), por lo
que las apps que solo usan funciones ligeras (process, cron, http, sqlite) dejan de
arrastrarlos. Reduccion de binarios: dag_engine 72->10MB, registry_api 70->8.7MB,
services_api 70->9MB, call_monitor 68->6.6MB, sqlite_api 70->8.9MB.

Los IDs del registry se mantienen estables (domain: infra en frontmatter). Se
preservan los build tags goolm/libolm de matrix_crypto_init.

Tambien corrige TestSSEHandler: el test leia el body con un unico Read() que con
HTTP chunked solo capturaba el primer evento; ahora usa io.ReadAll hasta EOF.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

functions/infra/clickhouse/clickhouse_open.go

@@ -0,0 +1,25 @@
+package clickhouse
+
+import (
+	"database/sql"
+	"fmt"
+
+	_ "github.com/ClickHouse/clickhouse-go/v2"
+)
+
+// ClickHouseOpen connects to a ClickHouse server and returns a *sql.DB.
+// Constructs a DSN of the form:
+//
+//	clickhouse://user:password@host:port/database
+func ClickHouseOpen(host string, port int, user, password, database string) (*sql.DB, error) {
+	dsn := fmt.Sprintf("clickhouse://%s:%s@%s:%d/%s", user, password, host, port, database)
+	db, err := sql.Open("clickhouse", dsn)
+	if err != nil {
+		return nil, fmt.Errorf("clickhouse_open: open: %w", err)
+	}
+	if err := db.Ping(); err != nil {
+		db.Close()
+		return nil, fmt.Errorf("clickhouse_open: ping %s:%d/%s: %w", host, port, database, err)
+	}
+	return db, nil
+}

functions/infra/clickhouse/clickhouse_open.md

@@ -0,0 +1,49 @@
+---
+name: clickhouse_open
+kind: function
+lang: go
+domain: infra
+version: "1.0.0"
+purity: impure
+signature: "func ClickHouseOpen(host string, port int, user, password, database string) (*sql.DB, error)"
+description: "Conecta a ClickHouse construyendo DSN clickhouse://user:pass@host:port/database."
+tags: [database, clickhouse, connection, sql, olap, pendiente-usar]
+uses_functions: []
+uses_types: [db_config_go_infra]
+returns: []
+returns_optional: false
+error_type: "error_go_core"
+imports: ["database/sql", "github.com/ClickHouse/clickhouse-go/v2"]
+params:
+  - name: host
+    desc: "hostname del servidor ClickHouse"
+  - name: port
+    desc: "puerto de ClickHouse (9000 para protocolo nativo, 8123 para HTTP)"
+  - name: user
+    desc: "nombre de usuario para autenticacion"
+  - name: password
+    desc: "contraseña para autenticacion"
+  - name: database
+    desc: "nombre de la base de datos a conectar"
+output: "conexion sql.DB abierta a ClickHouse con ping verificado"
+tested: false
+tests: []
+test_file_path: ""
+file_path: "functions/infra/clickhouse/clickhouse_open.go"
+---
+
+## Ejemplo
+
+```go
+db, err := ClickHouseOpen("localhost", 9000, "default", "", "analytics")
+if err != nil {
+    log.Fatal(err)
+}
+defer DBClose(db)
+
+rows, err := DBQuery(db, "SELECT event, count() FROM events GROUP BY event")
+```
+
+## Notas
+
+Usa el driver `github.com/ClickHouse/clickhouse-go/v2` registrado como "clickhouse". Puerto por defecto de ClickHouse es 9000 (nativo) o 8123 (HTTP). Hace ping al abrir para verificar conectividad.