chore(test + audit): add test-coverage audit + wire audit:all

#6 test coverage (pivot to reporting): 34/653 tests currently fail
(in-flight spaces-foundation migrations). Hard coverage thresholds
aren't enforceable until the suite is green, so this session ships a
file-presence audit instead of line-coverage gates.

  - scripts/audit-test-coverage.mjs — counts .svelte + .ts source files
    vs .test.ts + .spec.ts per module. Reports total ratio, lists
    modules with 0 tests + ≥3 source files (prioritised by size).
  - pnpm run audit:test-coverage  wires it into audit:*.
  - docs/optimizable/test-health.md — state + prevention path + top
    untested modules ranked by impact.

Current baseline: 2.6% file-level coverage. 66/78 modules have zero
tests. Biggest untested: times (32 src), articles (29), events (27),
inventory + skilltree (20 each).

#8 audit:all: single entry point for the reporting audits. Runs
port-drift + i18n-coverage + test-coverage in --summary mode. Distinct
from validate:all (which is gates, not reports).

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

docs/optimizable/test-health.md

@@ -0,0 +1,49 @@
+# Test Health
+
+**Status 2026-04-22.** Run `pnpm run audit:test-coverage` for live numbers.
+
+## Current state
+
+- **34/653 tests currently fail.** Related to in-flight
+  spaces-foundation migration work (app-registry, api-keys, base-client,
+  crypto record-helpers). Hard coverage thresholds aren't enforceable
+  until the suite is green.
+- **File-level "coverage" is 2.6%.** 22 test files vs 857 source files
+  (.svelte + .ts). 66 of 78 modules have zero tests.
+- **12 modules have ≥1 test file.** Hotspots (todo, times, body, a
+  handful of critical infra) are partially covered; long tail is not.
+
+## Why file presence, not line coverage
+
+Running `vitest --coverage` requires the suite to pass. Until the 34
+failing tests are fixed, coverage numbers are undefined. In the
+meantime, "does this module have *any* automated regression
+protection?" is a useful signal for prioritising the next session.
+
+## Top untested modules (by source file count)
+
+| Module | Source files | Priority |
+|---|---|---|
+| times | 32 | HIGH — time-tracking logic, billing-adjacent |
+| articles | 29 | HIGH — reader pipeline, bookmarklet, parsing |
+| events | 27 | MED — RSVP / calendar interactions |
+| inventory | 20 | MED — user-owned item schema |
+| skilltree | 20 | MED — XP / level math |
+| library | 19 | LOW — simple CRUD |
+| photos | 17 | MED — upload / storage paths |
+| wetter | 17 | LOW |
+| calc | 16 | MED — arithmetic correctness |
+| meditate, news, quotes, cards, core, moodlit | 13–16 each | mixed |
+
+## Prevention path
+
+1. **Fix the 34 failing tests first** — they're noise blocking any real
+   coverage work.
+2. **Run `vitest --coverage`** — capture a baseline per module.
+3. **Add thresholds to `vite.config.ts` `test.coverage.thresholds`**
+   — start lax (50% for modules with tests, ignore untested), tighten
+   over time.
+4. **Make `pnpm run test:coverage` part of `validate:all`** — only
+   after (1) is done.
+
+For now: `audit:test-coverage` is the contract.