diigo-cache: SQL in .sql files, behind a read-only facet

No SQL text in the cache logic any more. Statements live in two files,
parsed by sqlStatements (`-- name:` sections, as in finquick's
brcal/gcbook.js) and imported as text (wrangler Text rule for *.sql):

- cache-read.sql: selects only, checked when the module loads
- cache-write.sql: schema, the v2 renumbering, etch, drops

store.ts turns them into two frozen facets with domain methods:
makeReader(sql) runs only the read statements (page, knownTotal,
deepestPageSince, pagesThrough); makeWriter(storage) only the write
ones (migrate, etch, dropPagesThrough), each change one transaction.

The cache migrates in its constructor under blockConcurrencyWhile, as
Cloudflare recommends, so readers never meet missing tables; the
migration test plants v1 storage and evicts to get a fresh activation.
A viewer() facet (PageViewer: stored pages and fill progress, from the
reader alone) is added for the public page.

Pure refactor: stored state and behavior unchanged.

Generated-by: Claude Opus 5.5

diigo-cache/tests/sql-statements.test.ts

@@ -0,0 +1,15 @@
+import { describe, expect, it } from "vitest";
+import { sqlStatements } from "../src/sql-statements.js";
+
+describe("sqlStatements", () => {
+	it("splits a .sql file into named statements at each `-- name:` line, dropping the trailing ;", () => {
+		const text = "-- first:\nselect 1;\n\n-- second:\nselect *\nfrom t\nwhere a = ?;\n";
+		expect(sqlStatements(text)).toEqual({ first: "select 1", second: "select *\nfrom t\nwhere a = ?" });
+	});
+
+	it("keeps a multi-statement entry whole (inner semicolons stay)", () => {
+		expect(sqlStatements("-- both:\nupdate a set x = 1;\nupdate b set y = 2;\n")).toEqual({
+			both: "update a set x = 1;\nupdate b set y = 2",
+		});
+	});
+});