Add soroban_daily_metrics rollup schema

migrations/032_create_soroban_metrics_timeseries.sql

@@ -0,0 +1,26 @@
+-- Daily rollup schema for the Soroban Dashboard (issue #46).
+--
+-- This is aggregated data derived from the raw `contract_events` table
+-- (migration 022), NOT a duplicate of it -- #21-#24's endpoints should read
+-- from this table instead of aggregating raw events on every request.
+CREATE TABLE IF NOT EXISTS soroban_daily_metrics (
+    date TEXT NOT NULL, -- YYYY-MM-DD, UTC calendar day
+    contract_id TEXT NOT NULL, -- rolled up per-contract so #24's top-contracts
+                                -- ranking and per-contract drilldowns don't need
+                                -- to re-scan contract_events; a network-wide
+                                -- row uses contract_id = '__all__'
+    call_count INTEGER NOT NULL DEFAULT 0,
+    -- Total resource cost for the day, in stroops. NULL (not 0) means no cost
+    -- data was available for this contract/day -- see #23: contract_events
+    -- had no cost column until this same issue batch added one, so historical
+    -- rows predating that column will legitimately have no cost to roll up.
+    total_gas_stroops INTEGER,
+    active_contracts INTEGER NOT NULL DEFAULT 0, -- only meaningful on the
+                                                   -- '__all__' network-wide row
+    created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (date, contract_id)
+);
+
+CREATE INDEX IF NOT EXISTS idx_soroban_daily_metrics_date ON soroban_daily_metrics(date DESC);
+CREATE INDEX IF NOT EXISTS idx_soroban_daily_metrics_contract ON soroban_daily_metrics(contract_id, date DESC);