Add proboctl CLI and move seed commands into it

Introduce a new proboctl Cobra CLI for Probo instance management
that connects directly to PostgreSQL. Move the standalone
common-third-parties-import and common-tracker-patterns-import
commands into proboctl as `proboctl seed common-third-parties`
and `proboctl seed common-tracker-patterns`, replacing flag-based
PG connection with a shared factory pattern.

Signed-off-by: Émile Ré <emile@probo.com>

pkg/proboctl/cmdutil/cmdutil.go

@@ -0,0 +1,36 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package cmdutil
+
+import (
+	"fmt"
+
+	"go.gearno.de/kit/pg"
+	"go.probo.inc/probo/pkg/cmd/iostreams"
+	"go.probo.inc/probo/pkg/proboctl/pgconn"
+)
+
+type Factory struct {
+	IOStreams *iostreams.IOStreams
+	Version   string
+	PgDSN     string
+}
+
+func (f *Factory) PgClient() (*pg.Client, error) {
+	if f.PgDSN == "" {
+		return nil, fmt.Errorf("set --pg-dsn or DATABASE_URL")
+	}
+	return pgconn.NewPgClientFromDSN(f.PgDSN)
+}