docs(tests): add test coverage plans

tests/_plans/sqlexec.md

@@ -0,0 +1,20 @@
+# Plan: writers/sqlexec (19.4%)
+
+## Existing
+- `writer_test.go`: constructor, nil DB, missing conn string, empty scripts, script sorting, embed directives
+
+## Gaps
+
+| Item | Now | Approach |
+|------|-----|----------|
+| `Options` | 0% | Trivial getter |
+| `WriteDatabase` | 31.2% | Multi-schema; error from one schema aborts; context/connect failure |
+| `executeScripts` | 0% | Live via dbtest postgres (`RELSPEC_TEST_PG_CONN`); ordering by priority/sequence, failing script reports script name, empty SQL skipped, transaction/partial-apply behaviour as implemented |
+| `WriteSchema` | partial | Connection error path, success path live |
+
+## Data needed
+- Small script set (3-4 scripts, mixed priority, one failing) as fixtures; check `tests/assets` and `pkg/readers/sqldir` testdata first.
+- Cleanup: each live test uses a throwaway schema and drops it.
+
+## Decision
+- Live-only via `tests/dbtest/dbtest.sh test postgres ./pkg/writers/sqlexec/`; no connection interface or mock.