refactor(work): drop date prefixes + move _state.json into _system/

Convention shift: epic folders + PRD filenames + frontmatter id
fields are now bare slugs. The created: timestamp (Phase 2) carries
the date; folder names don't repeat it. A future <task-id>-<slug>
shape (e.g. ClickUp) lands cleanly when that integration ships.

Renames (git mv preserves history):
- docs/work/2026-05-13-binder-wrap-helper/
    -> docs/work/binder-wrap-helper/
- docs/work/2026-05-14-library-evaluation-policy/
    -> docs/work/library-evaluation-policy/
- docs/work/2026-05-14-ci-security-and-supply-chain/
    -> docs/work/ci-security-and-supply-chain/
- docs/work/prds/2026-05-13-binder-wrap-helper.prd.md
    -> docs/work/prds/binder-wrap-helper.prd.md
- docs/work/prds/2026-05-13-coverage-architecture.prd.md
    -> docs/work/prds/coverage-architecture.prd.md
- docs/work/prds/2026-05-14-library-evaluation-policy.prd.md
    -> docs/work/prds/library-evaluation-policy.prd.md
- docs/work/prds/2026-05-14-ci-security-and-supply-chain.prd.md
    -> docs/work/prds/ci-security-and-supply-chain.prd.md

Frontmatter updates inside the renamed files: epic id, epic prd,
story epic, PRD id, PRD builds-on all drop date prefixes.

System folder + state file move:
- New docs/work/_system/ holds framework-managed state.
- docs/work/_state.json -> docs/work/_system/_state.json.
- state-builder.mjs adds _system to SKIP_FOLDERS.
- cli.mjs + state-sync-guard.mjs + .husky/pre-commit point at the
  new path.

template-reset-v1 epic deleted entirely (one-off cleanup epic from
the pre-date-convention era; status was already done).

Generator-template updates (so new artifacts ship in the right
shape):
- .sandcastle/decomposer.prompt.md emits bare-slug folder names +
  ISO created: timestamp.
- .claude/skills/to-prd/SKILL.md template uses bare-slug filename +
  bare-slug id field + ISO created: timestamp.

Doc reference updates: glossary, runbook, agent-first-workflow-
and-conformance, reviewer prompt, ADR-020, ADR-022, ADR-023 all
point at the new paths/slugs.

docs/work/library-evaluation-policy/02-pre-commit-check-script/_story.md

@@ -0,0 +1,43 @@
+---
+id: 02-pre-commit-check-script
+epic: library-evaluation-policy
+title: Pre-commit check script for library trace presence
+type: technical-story
+status: done
+feature: scripts
+depends-on: [01-trace-schema-foundation]
+blocks: [06-sandcastle-reviewer-prompt]
+created: 2026-05-14T06:52:02+02:00
+updated: 2026-05-14T19:16:52.691Z
+---
+
+## Goal
+
+Write `scripts/library-decisions/check.mjs` — the script that walks staged `package.json` diffs, derives the tier of each affected package, and fails the commit when a new runtime dependency in a feature- or core-tier package has no sibling approved trace staged. Wire it into `.husky/pre-commit` as step 4.
+
+## Why
+
+Human and agent reviewers cannot reliably check trace presence during code review. The pre-commit hook is the last mechanical gate before a dep reaches the repo; it runs unconditionally, composes with `--no-verify` protection already in the bash-guard hook, and gives the committer immediate actionable feedback.
+
+## Done when
+
+- `scripts/library-decisions/check.mjs` exists and: (1) reads `git diff --cached --name-only -- '**/package.json'`; (2) for each staged `package.json`, derives tier from path (`apps/*` → app, `packages/core-*` → core, `packages/*` → feature); (3) for each newly added line in `dependencies` (not `devDependencies` / `peerDependencies`), checks that `docs/library-decisions/*-<name>.md` is also staged with `decision: approved`; (4) exits 1 with a per-package error report + pointer to the skill when any check fails; (5) app-tier and devdep additions exit 0 silently.
+- `.husky/pre-commit` invokes `node scripts/library-decisions/check.mjs` after the existing state-sync guard.
+- `scripts/library-decisions/check.test.mjs` covers (using a temp git repo fixture): new feature-tier dep without trace → exit 1; new feature-tier dep with approved trace staged → exit 0; new feature-tier dep with rejected-decision trace staged → exit 1; new app-tier dep → exit 0; new devdep → exit 0; multi-file diff with mixed pass/fail → exit 1 with per-package report; `peerDependencies`-only change → exit 0.
+- `pnpm typecheck && pnpm lint && pnpm test && pnpm conformance && pnpm fallow:audit && pnpm coverage:diff` all pass.
+
+## In scope
+
+- `scripts/library-decisions/check.mjs` — the check script (imports `schema.mjs` from Story 01 for trace validation).
+- `scripts/library-decisions/check.test.mjs` — integration tests using a temp git repo fixture (mirror pattern from `scripts/work/state-sync-guard.mjs` tests).
+- `.husky/pre-commit` — one added line.
+
+## Out of scope
+
+- Sandcastle reviewer prompt integration — Story 06.
+- `--staged-against <base>` flag for CI/sandcastle use — added in Story 06 when the reviewer prompt is written.
+- `pnpm libs check` ergonomic wrapper — deferred per PRD.
+
+## Tasks
+
+- [x] Write `scripts/library-decisions/check.mjs` (imports schema from Story 01; parses `git diff --cached` output; tier derivation from path; staged-trace presence + `decision: approved` check; exit-1 report with skill pointer); wire into `.husky/pre-commit`; write `check.test.mjs` integration tests with temp git repo fixture covering all 7 cases from Done when; all gates pass on this single commit.