docs: sell the standards, type-safety and defaults case, and give the landing page a narrative spine

[vivek7405]

Closes #1392

Two commits on website/ only. No framework source touched.

1. The claims the site was not making

Several things that are true of WebJs and that a reader decides on were stated nowhere on a marketing page.

• Web standards as a stance. The home hero listed the pieces (web components, SSR, progressive enhancement) without saying what they add up to. It now leads with leaning on web standards.
• No build, with a precedent. The Zero build step card asserted the bet and cited nothing. It now notes Rails has shipped its default frontend without a bundler since Rails 7 in 2021. Kept to one clause on purpose: articles/no-build-javascript-framework.md owns that keyword, and website/AGENTS.md forbids two pages chasing the same one.
• Full-stack type safety. Present on /docs/typescript and in a blog post, absent from all three marketing pages. Now on the home bento (the RPC card became Server actions, fully typed), in the code-windows lede, as a card on /why-webjs, and as a FAQ entry on /what-is-webjs.
• Defaults, not lock-in. /why-webjs listed what a scaffolded app arrives with and never said any of it was replaceable, which is exactly the objection that grid raises. A paragraph under the grid now says so, and the home templates section names the stack (light DOM, Tailwind, Drizzle, modules layout, tokens, the agent skill).
• The agent skill. Documented on /docs/ai-first, never sold on the pitch page. Now a card in ARRIVES.

2. A narrative spine for the landing page

The page listed seven true things and none of them set up the next, so nothing on it earned a scroll. Sections and order are unchanged; each lede now opens by picking up what the previous section closed on.

Section	The hand-off
Real HTML first	Frameworks got good at hiding the platform, and for years that paid for itself. What changed is when the bill arrives.
Nothing is compiled away (was Server action & SSR page)	That first paint is only honest if what you wrote is what shipped.
Modern full-stack, on web standards	Everything below falls out of that one decision.
Light enough for AI	A framework that compiles nothing away is a framework you can read.
Start where you are	All of it arrives in one command. (This section had no lede at all before.)

The opening beat credits the trade rather than mocking it, matching the register /why-webjs already uses for the same move.

Two things a future editor needs

Grid parity. Three grids here paint an empty cell in the grid's own border colour when the entry count goes odd (gap-px over bg-border). That is why type safety folded into the existing bento card instead of becoming a seventh, and why ARRIVES went 4 to 6 rather than to 5. A comment above ARRIVES records it.

The spine is fragile in a way no test catches. The hand-off lives in the first sentence of each lede, so rewriting one in isolation silently reverts the page to a spec sheet. A comment above STATS in page.ts records the chain and says so.

Verification

webjs typecheck clean, webjs check clean, webjs test --server 471/471. Booted locally and read end to end.