site-spec: expand into creative direction (layout, hero, typography)

[lezama]

What

Enhances the site-spec skill to auto-expand a vague brief into a creative direction — inferring layout, pages/sections, hero composition, and typography from the site name — then briefs the user in ≤4 lines before building.

Addresses @youknowriad's feedback on #3610: "we should not remove site spec, we should enhance it".

Why

When a user says "make a site for my bar", the current skill asks one binary question (one-page or multi-page?) and then the agent guesses everything else. The result is usually a minimal skeleton.

Telex's better output quality comes from two specific things it does before writing any file:

1. Hero composition — a short paragraph of cinematic prose describing the spatial layout (full-bleed / asymmetric / centered, image placement, typographic weight). This becomes the spatial anchor for all downstream block choices.
2. Typography inference — a font pairing derived from the site type (coffee shop → Fraunces + Spectral; law firm → Cormorant Garamond + Source Sans).

Both happen without asking the user anything extra.

Changes

• apps/cli/ai/skills/site-spec/SKILL.md — replaces the one-page/multi-page question with auto-expansion: layout mode, pages/sections, hero composition, typography. Also includes the Round 1 stop-instruction fix from site-spec: strengthen Round 1 stop instruction to prevent tool calls in same turn #3615.
• apps/cli/ai/system-prompt.ts — one-line update to the site-creation routing description.

2 files, +42/−17 lines.

Relationship to other PRs

• Supersedes the separate creative-direction skill in Add creative-direction skill for vague site briefs #3629 (draft/PoC) — same goal, one skill instead of two.
• Includes the Round 1 bug fix from site-spec: strengthen Round 1 stop instruction to prevent tool calls in same turn #3615.

Testing

npm run cli:build

1. "ayudame a crear un sitio para una hamburguesería" — agent should ask the name, stop, wait for reply, then auto-expand (layout + hero + typography) and brief you before building. No layout question.
2. "create a site called Bean & Brew" — agent should skip Round 1 (name already given), auto-expand directly, brief you, then build.

[wpmobilebot]

📊 Performance Test Results

Comparing 11343d7 vs trunk

app-size

Metric	trunk	11343d7	Diff	Change
App Size (Mac)	1335.89 MB	1335.89 MB	+0.00 MB	⚪ 0.0%

site-editor

Metric	trunk	11343d7	Diff	Change
load	1735 ms	1819 ms	+84 ms	🔴 4.8%

site-startup

Metric	trunk	11343d7	Diff	Change
siteCreation	9604 ms	9595 ms	9 ms	⚪ 0.0%
siteStartup	4922 ms	4916 ms	6 ms	⚪ 0.0%

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Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)