Tests, tooling and the served scripts are TypeScript (#392)

The page and the service worker were strict TypeScript; the tests, the
build, the home page's generator, the load tests, boot.js and the
directory's site.js were plain JavaScript that nothing checked. All of
it is TypeScript now, in five programs, each with its own globals, all
checked by npm run typecheck: the page (tsconfig.json, with boot.ts and
the directory's site.ts), the worker, Node's (tsconfig.tools.json: the
Node tests, the browser suite, the build, the site generator, the load
harness), and k6's (tsconfig.k6.json, with @types/k6).

Node 24 runs the .ts files by stripping their types, so they hold only
TypeScript that erases (erasableSyntaxOnly) and import each other by
.ts name; package.json says "type": "module" for it, and Dockerfile.web
moves to Node 24 to run build.mts. k6 2.3 strips its scripts' types
itself.

The browser suite's page.evaluate calls reach the page's globals; the
page's tsc run now also writes its declarations to target/page-types,
which the suite's program includes, so those calls are typed by the
page's own code rather than by hand-written copies.

boot.ts is compiled by build.mts with swc, as the worker is, and named
by the hash of what is served. The directory's build has no Node, so
site.js is compiled from site.ts and committed (node web/build.mts
--directory-script), and tests/directory-script.ts fails if they drift.

Checked: the site generator's 139 pages are byte for byte what the
JavaScript made; the page build's app.js is identical and only boot.js
(now minified) and its hash differ; contrast, page-smoke, page-unit,
native-bridge, the browser suite (96 passed, 2 skipped) and the
directory's and ipx's Rust tests pass; k6 parses each load script. The
load tests themselves did not run: they build a release binary outside
the capped builder. .agents/skills/security-audit is an installed
skill's, not ours, and is left as it is.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/types.ts

@@ -1,6 +1,6 @@
 // What ipx's API sends the page, as types for the type-check (#235), each named after the Rust
 // struct it mirrors in crates/ipx/src. Types only: swc strips this file to nothing, so it is not
-// in web/build.mjs's list; tsconfig.json's glob reads it. A field added there goes here too.
+// in web/build.mts's list; tsconfig.json's glob reads it. A field added there goes here too.
 // An Option is `T | null`, as serde writes None.
 
 /// A feed in your list, `/api/feeds` and the live `feed_row` (web.rs FeedRow).