fix(db): change prefix column type to TEXT in prefix_snapshot_row

Updated the prefix column in the prefix_snapshot_row table from CIDR to TEXT to accommodate broader input formats. Adjusted related SQL insert statements accordingly.

migrations/postgres/000016_prefix_snapshot.up.sql

@@ -10,7 +10,7 @@ CREATE TABLE prefix_snapshot (
 CREATE TABLE prefix_snapshot_row (
     snapshot_id   UUID NOT NULL REFERENCES prefix_snapshot (id) ON DELETE CASCADE,
     ord           INTEGER NOT NULL,
-    prefix        CIDR NOT NULL,
+    prefix        TEXT NOT NULL,
     community_id  UUID REFERENCES bgp_community (id) ON DELETE SET NULL,
     source        TEXT NOT NULL DEFAULT '',
     PRIMARY KEY (snapshot_id, ord)

migrations/postgres/000017_prefix_snapshot_backfill.up.sql

@@ -1,4 +1,8 @@
 -- Backfill prefix snapshots from revision_materialized_prefix.
+-- prefix_snapshot_row.prefix is TEXT (revision_materialized_prefix.prefix since 000003).
+
+ALTER TABLE prefix_snapshot_row
+    ALTER COLUMN prefix TYPE TEXT USING prefix::text;
 
 WITH new_snaps AS (
     INSERT INTO prefix_snapshot (id, content_hash)