feat: import existing publications from XML (story #05)

scripts/import_publications.py imports all osw=1 publications from
03-data/osws.xml — upserts pub rows, loads cover images, scans
03-data/osdb/{pubId}/ for fruit images and PDFs, links matched fruits
by osdb_number. Idempotent re-runs. 17 unit tests. Makefile updated
to include import_publications_test in make test. Added
scripts/README_import.md with run order. Added spec-first rule to
.claude/CLAUDE.md.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/README_import.md

@@ -0,0 +1,37 @@
+# Import Scripts
+
+## Prerequisites
+
+- Postgres running and migrated (`make migrate-up`)
+- `DATABASE_URL` set, e.g.:
+  ```
+  export DATABASE_URL=postgres://user:pass@localhost:5432/osdb
+  ```
+- `03-data/` directory present at repo root
+- `psycopg2` installed (`pip install psycopg2-binary`)
+
+---
+
+## Run Order
+
+Scripts must be run in order — publications import depends on fruits being present.
+
+### 1. Import fruits
+
+```bash
+DATABASE_URL=... python3 scripts/import_fruits.py
+```
+
+Imports fruits, synonyms, and fruit images from `03-data/obstsorten.xml`.
+Idempotent: upserts fruits by `osdb_number`.
+
+### 2. Import publications
+
+```bash
+DATABASE_URL=... python3 scripts/import_publications.py
+```
+
+Imports publications from `03-data/osws.xml` (only `<obj>` elements with `<osw>=1`).
+For each publication: upserts the row, loads cover image, links fruits found by
+filesystem scan of `03-data/osdb/{pubId}/`, and imports PDFs and fruit images.
+Idempotent: clears and re-inserts linked data on re-run.