docs(v1): README hero reframe + writing-style + CHANGELOG + version bump to 1.0.0.0

README.md:
- Hero removes "600,000+ lines of production code" framing; replaces
  with the computed 2013-vs-2026 pro-rata multiple (via
  <!-- GSTACK-THROUGHPUT-PLACEHOLDER --> anchor, filled by the
  update-readme-throughput build step).
- Hiring callout: "ship real products at AI-coding speed" instead of
  "10K+ LOC/day."
- New Writing Style section (~80 words) between Quick start and
  Install: "v1 prompts = simpler" framing, outcome-language example,
  terse-mode opt-out, pointer to /plan-tune.

CLAUDE.md: one-paragraph Writing style (V1) note under project
conventions, linking to preamble resolver + V1 design docs.

CHANGELOG.md: V1 entry on top of v0.19.0.0 with user-facing narrative
(what changes, how to opt out, for-contributors notes). Mentions
scope reduction — pacing overhaul ships in V1.1.

CONTRIBUTING.md: one-paragraph note on jargon-list.json maintenance
(PR to add/remove terms; regenerate via gen:skill-docs).

VERSION + package.json: bump to 1.0.0.0.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -179,6 +179,18 @@ Rules:
 - **Express conditionals as English.** Instead of nested `if/elif/else` in bash,
   write numbered decision steps: "1. If X, do Y. 2. Otherwise, do Z."
 
+## Writing style (V1)
+
+Default output from every tier-≥2 skill follows the Writing Style section in
+`scripts/resolvers/preamble.ts`: jargon glossed on first use (curated list in
+`scripts/jargon-list.json`, baked at gen-skill-docs time), questions framed in
+outcome terms ("what breaks for your users if...") not implementation terms,
+short sentences, decisions close with user impact. Power users who want the
+tighter V0 prose set `gstack-config set explain_level terse` (binary switch,
+no middle mode). See `docs/designs/PLAN_TUNING_V1.md` for the full design
+rationale. The review pacing overhaul that originally tried to ride alongside
+writing-style was extracted to V1.1 — see `docs/designs/PACING_UPDATES_V0.md`.
+
 ## Browser interaction
 
 When you need to interact with a browser (QA, dogfooding, cookie setup), use the