graph/db+sqldb: impl PruneGraph, PruneTip, ChannelView

Which lets us run `TestGraphPruning` and `TestBatchedAddChannelEdge`
against our SQL backends.

sqldb/sqlc/queries/graph.sql

@@ -212,6 +212,16 @@ RETURNING id;
 SELECT * FROM channels
 WHERE scid = $1 AND version = $2;
 
+-- name: GetChannelByOutpoint :one
+SELECT
+    sqlc.embed(c),
+    n1.pub_key AS node1_pubkey,
+    n2.pub_key AS node2_pubkey
+FROM channels c
+    JOIN nodes n1 ON c.node_id_1 = n1.id
+    JOIN nodes n2 ON c.node_id_2 = n2.id
+WHERE c.outpoint = $1;
+
 -- name: GetChannelAndNodesBySCID :one
 SELECT
     c.*,
@@ -411,6 +421,13 @@ WHERE node_1_signature IS NOT NULL
   AND scid >= @start_scid
   AND scid < @end_scid;
 
+-- name: ListChannelsPaginated :many
+SELECT id, bitcoin_key_1, bitcoin_key_2, outpoint
+FROM channels c
+WHERE c.version = $1 AND c.id > $2
+ORDER BY c.id
+LIMIT $3;
+
 -- name: ListChannelsWithPoliciesPaginated :many
 SELECT
     sqlc.embed(c),
@@ -648,3 +665,23 @@ SELECT EXISTS (
     WHERE scid = $1
     AND version = $2
 ) AS is_zombie;
+
+/* ─────────────────────────────────────────────
+    prune_log table queries
+    ─────────────────────────────────────────────
+*/
+
+-- name: UpsertPruneLogEntry :exec
+INSERT INTO prune_log (
+    block_height, block_hash
+) VALUES (
+    $1, $2
+)
+ON CONFLICT(block_height) DO UPDATE SET
+    block_hash = EXCLUDED.block_hash;
+
+-- name: GetPruneTip :one
+SELECT block_height, block_hash
+FROM prune_log
+ORDER BY block_height DESC
+LIMIT 1;