Exclude !post from the daily cap

Manual !post overrides were counted toward daily_cap_total, so a few
forced posts could starve the round-robin rotation for the rest of the
day. Tag forced rows in post_log and skip them in CountAllPostsInWindow
so the cap only meters the auto-rotation.

internal/scheduler/roundrobin_test.go

@@ -156,7 +156,7 @@ func TestTick_AlreadyPostedExcluded(t *testing.T) {
 	setupTestDB(t)
 	insertPostable(t, "t-posted", "GuardianTech", "tech", 200)
 	insertPostable(t, "t-fresh", "GuardianTech", "tech", 100)
-	storage.InsertPostLog("t-posted", "tech", "$evt1", "https://example.com/t-posted")
+	storage.InsertPostLog("t-posted", "tech", "$evt1", "https://example.com/t-posted", false)
 
 	fq := &fakeQueue{}
 	rr := New([]string{"tech"}, 4, fq)