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>

CHANGELOG.md

@@ -1,5 +1,29 @@
 # Changelog
 
+## [1.0.0.0] - 2026-04-18
+
+### Added
+- **v1 prompts = simpler.** Every skill's output (tier 2 and up) explains technical terms on first use with a one-sentence gloss, frames questions in outcome terms ("what breaks for your users if..." instead of "is this endpoint idempotent?"), and keeps sentences short and direct. Good writing for everyone — not just non-technical folks. Engineers benefit too.
+- **Terse opt-out for power users.** `gstack-config set explain_level terse` switches every skill back to the older, tighter prose style — no glosses, no outcome-framing layer. Binary switch, sticks across all skills.
+- **Curated jargon list.** A repo-owned list of ~50 technical terms (idempotent, race condition, N+1, backpressure, and friends) at `scripts/jargon-list.json`. These are the terms gstack glosses. Terms not on the list are assumed plain-English enough. Add terms via PR.
+- **Real LOC receipts in the README.** Replaced the "600,000+ lines of production code" hero framing with a computed 2013-vs-2026 pro-rata multiple on logical code change, with honest caveats about public-vs-private repos. The script that computes it is at `scripts/garry-output-comparison.ts` and uses [scc](https://github.com/boyter/scc). Raw LOC is still in `/retro` output for context, just no longer the headline.
+- **Smarter `/retro` metrics.** `/retro` now leads with features shipped, commits, and PRs merged — logical SLOC added comes next, and raw LOC is demoted to context-only. Because ten lines of a good fix is not less shipping than ten thousand lines of scaffold.
+- **Upgrade prompt on first run.** When you upgrade to this version, the first skill you run will ask once whether you want to keep the new default writing style or restore V0 prose with `gstack-config set explain_level terse`. One-time, flag-file gated, never asks again.
+
+### Changed
+- **README hero reframed.** No more "10K-20K lines per day" claim. Focuses on products shipped + features + the pro-rata multiple on logical code change, which is the honest metric now that AI writes most of the code. The point isn't who typed it, it's what shipped.
+- **Hiring callout reframed.** Replaced "ship 10K+ LOC/day" with "ship real products at AI-coding speed."
+
+### For contributors
+- New `scripts/resolvers/preamble.ts` Writing Style section, injected for tier ≥ 2 skills. Composes with the existing AskUserQuestion Format section (Format = how the question is structured, Style = the prose quality of the content inside). Jargon list is baked into generated SKILL.md prose at `gen-skill-docs` time — zero runtime cost, edit the JSON and regenerate.
+- New `bin/gstack-config` validation for `explain_level` values. Unknown values print a warning and default to `default`. Annotated header documents the new key.
+- New one-shot upgrade migration at `gstack-upgrade/migrations/v1.0.0.0.sh`, matching existing `v0.15.2.0.sh` / `v0.16.2.0.sh` pattern. Flag-file gated.
+- New throughput pipeline: `scripts/garry-output-comparison.ts` (scc preflight + author-scoped SLOC across 2013 + 2026), `scripts/update-readme-throughput.ts` (reads the JSON, replaces `<!-- GSTACK-THROUGHPUT-PLACEHOLDER -->` anchor), `scripts/setup-scc.sh` (OS-detecting installer invoked only when running the throughput script — scc is not a package.json dependency).
+- Two-string marker pattern in README to prevent the pipeline from destroying its own update path: `GSTACK-THROUGHPUT-PLACEHOLDER` (stable anchor) vs `GSTACK-THROUGHPUT-PENDING` (explicit missing-build marker CI rejects).
+- V0 dormancy negative tests — the 5D psychographic dimensions (scope_appetite, risk_tolerance, detail_preference, autonomy, architecture_care) and 8 archetype names (Cathedral Builder, Ship-It Pragmatist, Deep Craft, Taste Maker, Solo Operator, Consultant, Wedge Hunter, Builder-Coach) must not appear in default-mode skill output. Keeps the V0 machinery dormant until V2.
+- **Pacing improvements ship in V1.1.** The scope originally considered (review ranking, Silent Decisions block, max-3-per-phase cap, flip mechanism) was extracted to `docs/designs/PACING_UPDATES_V0.md` after three engineering-review passes revealed structural gaps that couldn't be closed with plan-text editing. V1.1 picks it up with real V1 baseline data.
+- Design doc: `docs/designs/PLAN_TUNING_V1.md`. Full review history: CEO + Codex (×2 passes, 45 findings integrated) + DX (TRIAGE) + Eng (×3 passes — last pass drove the scope reduction).
+
 ## [0.19.0.0] - 2026-04-17
 
 ### Added