docs(ultraplan-local): v2.3.0 — skill-factory Fase 1

Doc sync for /ultra-skill-author-local release:

- CHANGELOG.md: 2.3.0 section above 2.2.0 with full feature narrative,
  pipeline diagram, non-goals, new files list, new stats file
- README.md: command table row + new ## /ultra-skill-author-local section
  describing pipeline, modes, IP-hygiene utility, non-goals
- CLAUDE.md: row in Commands table (committed in Step 1)
- ../../README.md: bumped ultraplan-local row v2.2.0 → v2.3.0,
  expanded division-of-labor with sixth bullet for /ultra-skill-author-local,
  added v2.3 narrative paragraph

Plan: .claude/projects/2026-04-18-skill-factory-fase-1-mvp/plan.md (step 12)

plugins/ultraplan-local/README.md

@@ -13,6 +13,7 @@ A [Claude Code](https://docs.anthropic.com/en/docs/claude-code) plugin for deep
 | **`/ultra-cc-architect-local`** | Architect (optional) — match brief+research against available CC features; produce architecture note with explicit gaps |
 | **`/ultraplan-local`** | Plan — agent swarm exploration, Opus planning, adversarial review |
 | **`/ultraexecute-local`** | Execute — disciplined step-by-step implementation with failure recovery |
+| **`/ultra-skill-author-local`** | Authoring (v2.3, skill-factory Fase 1) — generate one cc-architect-catalog draft from a local source with IP-hygiene |
 
 Every artifact lives in one project directory: `.claude/projects/{YYYY-MM-DD}-{slug}/` contains `brief.md`, `research/NN-*.md`, `architecture/overview.md` (+ `gaps.md`), `plan.md`, `sessions/`, and `progress.json`.
 
@@ -395,6 +396,52 @@ The executor implements defense-in-depth security across four layers:
 
 ---
 
+## `/ultra-skill-author-local` — Authoring *(skill-factory Fase 1, v2.3)*
+
+Manual one-skill-at-a-time generator for the `cc-architect-catalog`. Channel 2 of the skill-factory strategy: a curated local source enters, one draft skill exits in `skills/cc-architect-catalog/.drafts/` with its n-gram containment score against the source stamped into the frontmatter (or the draft is deleted when the overlap is too high).
+
+### Why it exists
+
+`/ultra-cc-architect-local` enforces a hallucination gate that only permits feature proposals backed by the catalog. With 10 seed skills covering 8 features × 2 layers, the matcher rarely finds support and silently produces empty proposals. This command grows the catalog without spinning up automation: one source → one draft → manual review → manual `mv` for promotion.
+
+### Pipeline
+
+Sequential, no retry, no parallelism:
+
+```
+/ultra-skill-author-local <source>
+  → concept-extractor (sonnet)    → JSON: cc_feature, layer, slug
+  → skill-drafter (sonnet)        → .drafts/<slug>.md, 9-field frontmatter
+  → ip-hygiene-checker (sonnet)   → runs scripts/ngram-overlap.mjs
+        verdict accepted/needs-review → stamp ngram_overlap_score
+        verdict rejected               → rm draft (no preservation)
+```
+
+### Modes
+
+| Mode | Usage | Behavior |
+|------|-------|----------|
+| **Default** | `/ultra-skill-author-local <source>` | Run the pipeline (concept → draft → IP-hygiene) foreground |
+| **`--fg`** | `/ultra-skill-author-local <source> --fg` | Same as default; flag accepted for pipeline-convention consistency |
+| **`--quick`** | `/ultra-skill-author-local <source> --quick` | Skip IP-hygiene with BIG WARNING (drafting-pipeline test only) |
+
+### IP-hygiene utility
+
+`scripts/ngram-overlap.mjs` — pure Node stdlib, zero dependencies. Word-5-gram containment similarity (asymmetric draft⊆source) plus longest-consecutive-shingle-run secondary signal. Verdict bands: `accepted` (<0.15 AND <8), `needs-review` (mid), `rejected` (≥0.35 OR ≥15). Short-text fallback to n=4 when min(words) <500. CLI emits JSON.
+
+Calibration fixtures in `tests/fixtures/skill-factory/` pin the verdict bands against representative prose. Re-verify any threshold change against these fixtures.
+
+### Non-goals (explicit, Fase 1)
+
+- No automation, cron, or watcher
+- No CC changelog diffing or auto-research
+- No batch processing or review command
+- No decision-layer skills (cross-feature comparison is Fase 2+)
+- No URL or remote sources — local files only
+- Manual `mv` from `.drafts/` to catalog root is the promotion mechanism
+
+---
+
 ## The full pipeline
 
 ```