perf(parser): write the databases with 1 KiB pages

The browser fetches this file one page per HTTP request, so the page size
is the granularity of every read. At SQLite's 4 KiB default a row reached
by an index seek dragged 4 KB across the network; at 1 KiB it drags 1 KB.
A name search returns up to 100 scattered rows, so its row fetches fall
from about 400 KB to about 100 KB.

Measured on the rebuilt 2016 file: 6.3 rows share a page where 27 did.
The index walks are sequential and unaffected in bytes — the library's
read-ahead already collapses those into few requests.

Cost is 4% file size: 2016 288.6 -> 302.4 MB, 2017 237.7 -> 247.3 MB,
the site 528 -> 552 MB against the 1 GB GitHub Pages limit. Both
sql.js-httpvfs and sqlite-wasm-http recommend this page size.

The PRAGMA has to run before the DDL, since a page size is fixed once a
table exists, and requestChunkSize on the client has to match or every
page read spans two requests.

Row counts unchanged and through the assembler guards; query plans
re-checked and still index-driven on the rebuilt files.

web/src/lib/sqlite.svelte.ts

@@ -14,8 +14,10 @@ import wasmUrl from "sql.js-httpvfs/dist/sql-wasm.wasm?url";
  * the byte budget below is for.
  */
 
-// Matches the page size the parser writes, so one request is one page.
-const CHUNK_BYTES = 4096;
+// Must equal the page size the parser writes (PRAGMA page_size in
+// parser/internal/writer/writer.go), so one request is exactly one page. A
+// mismatch makes every logical page read span two requests.
+const CHUNK_BYTES = 1024;
 
 /** Generous for indexed work: a name search costs well under 1 MB. */
 export const SEARCH_BUDGET_BYTES = 25 * 1024 * 1024;