Fix comments and docs left stale by the alert deferral, tutorial, and Lath tool work

[dormouse-bot]

This fixes seven comments and doc lines that no longer match the code. Six change only comments or docs. The seventh brings a test helper's default in line with what its doc comment already claimed.

• lib/src/lib/alert-settings-model.ts: the deferAlertsUntilQuiet doc still described the old rule, "five seconds after the last accepted output". Deferral now holds only while the output detector has confirmed work (isConfirmedBusy() in alert-manager.ts), as of Use the output detector for alert deferral #1083.
• website/src/lib/tutorial-shell.test.ts: the OSC 633 block comment named the removed WATCHING/command-exit demos. It now names the Alerts section's agent and build programs from Teach alerts with real commands in the playground #1082.
• lib/src/lib/lath/test-fixtures.ts: leafMeta claimed to default tabComponent "the same way the real builders do", but it mapped tool to surface. toolLeafMeta in lath-wall-engine.ts gives tool → tool. The helper and its doc now include that mapping. No test calls leafMeta with component: 'tool', so no test's behavior changes.
• lib/src/remote/burrow/push-delivery.test.ts: fakeSeal's comment said the cases "mint no keys". The file's beforeAll mints real X25519 keys, so that clause is removed.
• scripts/pairing-walkthrough/cdp.mjs: it pointed at a README heading "The Pocket browser" that doesn't exist. The text it means is under "Known limitations".
• docs/compatible-agents.md: it quoted a test title, which AGENTS.md rules out ("never quote a test title"). It now cites only the test file.
• docs/specs/hosted.md: a stray double comma.

pnpm lint:specs passes locally. No regression test, because the only code change is to a test fixture.

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[dormouse-bot]

Workflow Lint is red on this head, but not because of this diff. zizmor's impostor-commit audit rejects the dtolnay/rust-toolchain@89b12181fb390509a0842a86cc55eeb8eb928c1d # stable pin at ci.yml:263, ci.yml:352, and release.yml:59. Upstream rewrote stable (now 686976e191b8), and the GitHub compare API reports the pinned commit as diverged from it. main last passed CI before that rewrite. Its next run will fail the same way, so the pin needs re-pinning in a separate change. The comment and doc fixes here all match the code they describe.