feat(backend): adapt feed fetch interval to update frequencyHEADmain

Add per-feed fetch_interval_seconds (clamped to [1h, 24h]) that halves
on new articles and grows 1.5x when a fetch yields nothing, replacing
the fixed 1h schedule with the 10min cooldown filter. Scheduler tick
shortened to 30min so the 1h floor is honored with reasonable precision.

1 files changed, 7 insertions, 6 deletions

diff --git a/backend/db/models.go b/backend/db/models.go
index e397102..342d6a0 100644
--- a/backend/db/models.go
+++ b/backend/db/models.go
@@ -14,12 +14,13 @@ type Article struct {
 }
 
 type Feed struct {
-	ID           int64
-	Url          string
-	Title        string
-	FetchedAt    string
-	IsSubscribed int64
-	UserID       int64
+	ID                   int64
+	Url                  string
+	Title                string
+	FetchedAt            string
+	IsSubscribed         int64
+	UserID               int64
+	FetchIntervalSeconds int64
 }
 
 type User struct {