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, so nothing that reads a target parses
it. 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.

Model: opus-5-5

internal/handlers/event_resubmit_test.go

@@ -151,7 +151,7 @@ func TestHandleEventResubmit_DeliversToTargetCreatedAfterTheEvent(
 	// captured. It has no prior delivery of anything.
 	tgt := seedConfiguredTarget(
 		t, db, wh.ID, database.TargetTypeHTTP,
-		`{"url":"`+resubmitTargetURL+`"}`,
+		database.Target{URL: resubmitTargetURL},
 	)
 
 	w := postResubmit(t, h, sess, wh.ID, original.ID)
@@ -274,7 +274,7 @@ func TestHandleEventResubmit_IsRepeatable(t *testing.T) {
 	wh := seedWebhook(t, db)
 	tgt := seedConfiguredTarget(
 		t, db, wh.ID, database.TargetTypeHTTP,
-		`{"url":"`+resubmitTargetURL+`"}`,
+		database.Target{URL: resubmitTargetURL},
 	)
 	original := seedStoredEvent(t, dbMgr, wh.ID, `{"fire":"again"}`)
 
@@ -368,7 +368,7 @@ func TestHandleEventResubmit_OversizeBodySurvivesIntact(t *testing.T) {
 	wh := seedWebhook(t, db)
 	seedConfiguredTarget(
 		t, db, wh.ID, database.TargetTypeHTTP,
-		`{"url":"`+resubmitTargetURL+`"}`,
+		database.Target{URL: resubmitTargetURL},
 	)
 	original := seedStoredEvent(t, dbMgr, wh.ID, stored)
 
@@ -425,11 +425,11 @@ func TestHandleEventResubmit_SkipsInactiveTarget(t *testing.T) {
 	wh := seedWebhook(t, db)
 	active := seedConfiguredTarget(
 		t, db, wh.ID, database.TargetTypeHTTP,
-		`{"url":"`+resubmitTargetURL+`"}`,
+		database.Target{URL: resubmitTargetURL},
 	)
 	off := seedConfiguredTarget(
 		t, db, wh.ID, database.TargetTypeHTTP,
-		`{"url":"`+resubmitTargetURL+`/off"}`,
+		database.Target{URL: resubmitTargetURL + "/off"},
 	)
 
 	require.NoError(t, db.DB().Model(&database.Target{}).
@@ -528,7 +528,7 @@ func TestHandleEventResubmit_RefusesEventOfAnotherWebhook(
 	mine := seedWebhook(t, db)
 	seedConfiguredTarget(
 		t, db, mine.ID, database.TargetTypeHTTP,
-		`{"url":"`+resubmitTargetURL+`"}`,
+		database.Target{URL: resubmitTargetURL},
 	)
 	seedStoredEvent(t, dbMgr, mine.ID, `{"mine":true}`)
 
@@ -575,7 +575,7 @@ func TestHandleSourceLogs_ShowsResubmitProvenance(t *testing.T) {
 	wh := seedWebhook(t, db)
 	seedConfiguredTarget(
 		t, db, wh.ID, database.TargetTypeHTTP,
-		`{"url":"`+resubmitTargetURL+`"}`,
+		database.Target{URL: resubmitTargetURL},
 	)
 	original := seedStoredEvent(t, dbMgr, wh.ID, `{"trace":"me"}`)