fix(terminal): deadline must cover the body, precache must ignore the cache-bust query

Review fixes. Two of these are defects in the previous commit.

1. The fetch deadline only covered time-to-headers. `await fetch()` settles on
   response headers, so clearing the abort timer in a finally around it left the
   body — the multi-megabyte `?full=1` capture the deadline exists for —
   completely unbounded; it only ever bounded a server that accepts a connection
   and never replies. Measured against a server that sends headers immediately
   and stalls the body 4s under a 1s deadline: fetch resolved at 30ms, timer
   cleared there, body completed at 4026ms unaborted. Now the body is read
   inside `_fetchTerminalCapture`, which returns {json, headers, headersAt} —
   headers because two callers read server-timing, headersAt because those same
   callers measure header-vs-body time and can no longer observe that moment.
   `_terminalCaptureInflight` is scoped the same way, so a body still streaming
   counts toward a capture starting beside it. Same test now aborts at 1005ms.

2. The precache could never be hit, and the previous commit made that expensive
   rather than free. `renderIndexHtml` runs `cacheBustAssets`, which appends
   `?v=<mtime>` to every same-origin .js/.css reference INCLUDING content-hashed
   names — confirmed against a running instance:
   `vendor/xterm-zerolag-input.6fee72f2.js?v=1789402869101`. `caches.match` is
   query-sensitive, so entries keyed on the bare hashed path were unreachable;
   deriving the list from the manifest turned cheap 404s into ~1.3MB downloaded
   at every install that nothing could read back, once per deploy now that
   CACHE_NAME rotates. The fallback match takes `{ ignoreSearch: true }`, which
   also lets runtime-cached entries survive an mtime change.

3. `_wsOutputGapSession` was only cleared in ws.onopen, so paths that already
   repaint the buffer left it set and the socket replayed everything a second
   time. `selectSession` loads the buffer and only THEN calls `_connectWs`, so
   neither the _isLoadingBuffer nor the _terminalRefreshOwner guard applied.
   `_markTerminalBufferReconciled()` is now called from _onSessionNeedsRefresh's
   finally, from selectSession after its load, and from _cleanupSessionData.

   The scope claim was also wrong and is corrected in the comment: when the
   network drops, SSE drops with it and handleInit's keepTerminal branch already
   reconciles. The genuinely uncovered case is the WS dying while SSE stays up,
   where _onSSETerminal discards SSE terminal frames until _wsReady flips in
   onclose — up to the ping+pong window of output nothing writes.

4. CLAUDE.md said "all of them measured rather than reasoned", which the PR's
   own "not verified" section contradicted. Split explicitly: the replay race is
   measured, the watchdog mechanism is verified against xterm 6.0.0 under jsdom
   (field path resolves, a forced stale handle makes refreshRows a no-op, the
   kick schedules a fresh frame), and the iOS rAF-discard premise is reasoned
   and still wants a device. Adds the two missing entries — the WebSocket
   reconcile and the sw.js/build.mjs "keep these in sync or the build throws"
   contract.

Also: test/xterm-private-api.test.ts pins the RESOLVED lockfile version instead
of the declared `^6.0.0` range, which was the wrong assertion in both directions
— a real upgrade to 6.4.0 can rename a private field while resolving inside the
range, and an innocuous range edit failed while changing nothing installed. And
test/sw-precache-manifest.test.ts now parses HASHABLE out of scripts/build.mjs
rather than hand-copying it, which was the same drift this PR exists to fix; the
parse is guarded against silently matching nothing.

The deadline fix has a behavioural test against a real socket plus a source
guard asserting `await res.json()` precedes the finally — verified to fail when
the helper is reverted to the old shape, so it is not vacuous.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

test/xterm-private-api.test.ts

@@ -28,23 +28,29 @@ import { resolve } from 'node:path';
 import { describe, expect, it } from 'vitest';
 
 const root = resolve(import.meta.dirname, '..');
-const pkg = JSON.parse(readFileSync(resolve(root, 'package.json'), 'utf8')) as {
-  dependencies: Record<string, string>;
+const lock = JSON.parse(readFileSync(resolve(root, 'package-lock.json'), 'utf8')) as {
+  packages: Record<string, { version?: string }>;
 };
 const terminalUi = readFileSync(resolve(root, 'src/web/public/terminal-ui.js'), 'utf8');
 
-// The major line `_kickRenderer`'s field path was verified against.
-const VERIFIED_XTERM_RANGE = '^6.0.0';
+// The exact version `_kickRenderer`'s field path was verified against.
+//
+// Read from the LOCKFILE, not package.json. The declared range is `^6.0.0`, so
+// asserting on that string is the wrong test in both directions: a real upgrade
+// to 6.4.0 — which can absolutely rename a private field — resolves inside the
+// range and slips through, while an innocuous range edit that changes nothing
+// about the installed code fails. The lockfile is what actually ships.
+const VERIFIED_XTERM_VERSION = '6.0.0';
 
 describe('xterm private-API dependency guard', () => {
-  it('pins the xterm range _kickRenderer was verified against', () => {
+  it('pins the resolved xterm version _kickRenderer was verified against', () => {
     expect(
-      pkg.dependencies['@xterm/xterm'],
-      'xterm moved off the verified range — re-verify _kickRenderer in a real browser ' +
+      lock.packages['node_modules/@xterm/xterm']?.version,
+      'xterm moved off the verified version — re-verify _kickRenderer in a real browser ' +
         '(terminal-ui.js: _core._renderService._renderDebouncer._animationFrame), then update ' +
-        'VERIFIED_XTERM_RANGE here. The accessor is optional-chained, so a renamed field ' +
+        'VERIFIED_XTERM_VERSION here. The accessor is optional-chained, so a renamed field ' +
         'degrades to a silent no-op and the freeze it heals comes back unnoticed.'
-    ).toBe(VERIFIED_XTERM_RANGE);
+    ).toBe(VERIFIED_XTERM_VERSION);
   });
 
   // If someone deletes the watchdog, this guard is pointless noise — keep the