Store a target's settings as columns (closes #543)

A target's settings move from the per-type JSON string in
targets.config to columns: url, headers, timeout_seconds,
forward_query, archive_expiry and archive_rotation. A column a type
does not use stays empty. headers holds the header map as JSON text
through GORM's JSON serializer, and archive_expiry holds a
time.Duration, 0 meaning never. The forms check each setting once,
with the same refusals and messages, and the edit form is filled from
the columns, so the per-type config structs, their parsers and the
"could not be read" branches are gone. A delivery task carries the
six settings in place of the JSON string; tests check that each copy
into a task, and back out of one, keeps all six.

Model: opus-5-5

internal/archive/evict_test.go

@@ -37,9 +37,9 @@ func TestEvictWebhook_ClosesAndRemovesWriter(t *testing.T) {
 	t.Parallel()
 
 	env := setupArchiveTest(t)
-	first := env.seedDatabaseTarget(t, "")
-	second := env.addDatabaseTarget(t, first.WebhookID, "")
-	other := env.seedDatabaseTarget(t, "")
+	first := env.seedDatabaseTarget(t, 0, "")
+	second := env.addDatabaseTarget(t, first.WebhookID, 0, "")
+	other := env.seedDatabaseTarget(t, 0, "")
 
 	for _, tgt := range []*database.Target{first, second, other} {
 		deliverTo(t, env, tgt)
@@ -80,8 +80,8 @@ func TestEvictTarget_LeavesOtherTargets(t *testing.T) {
 	t.Parallel()
 
 	env := setupArchiveTest(t)
-	doomed := env.seedDatabaseTarget(t, "")
-	kept := env.addDatabaseTarget(t, doomed.WebhookID, "")
+	doomed := env.seedDatabaseTarget(t, 0, "")
+	kept := env.addDatabaseTarget(t, doomed.WebhookID, 0, "")
 
 	deliverTo(t, env, doomed)
 	deliverTo(t, env, kept)
@@ -310,7 +310,7 @@ func TestEvictWebhook_RacingWriteDoesNotReopenHandle(
 	t.Parallel()
 
 	env := setupArchiveTest(t)
-	tgt := env.seedDatabaseTarget(t, "")
+	tgt := env.seedDatabaseTarget(t, 0, "")
 
 	// Prime the registry so the test can hold the very writer the
 	// eviction is about to detach.
@@ -355,7 +355,7 @@ func TestEvictWebhook_LaterDeliveryRecreatesWriter(t *testing.T) {
 	t.Parallel()
 
 	env := setupArchiveTest(t)
-	tgt := env.seedDatabaseTarget(t, "")
+	tgt := env.seedDatabaseTarget(t, 0, "")
 
 	deliverTo(t, env, tgt)
 	require.True(t, env.writers.ExportHasArchiveWriter(tgt.ID))
@@ -380,7 +380,7 @@ func TestEvictAll_WriteAfterIsRefused(t *testing.T) {
 	t.Parallel()
 
 	env := setupArchiveTest(t)
-	tgt := env.seedDatabaseTarget(t, "")
+	tgt := env.seedDatabaseTarget(t, 0, "")
 
 	deliverTo(t, env, tgt)