feat: search materials through beachcomber

- Material is a beachcomber Searchable (index jz_bm_materials) in the
  hand-written models/material_search.go; jz.bm requires summercms v0.6.4
- classes.MaterialIndexer asks Typesense for up to 250 candidates with
  body highlights; the app-wide Gate is on only for jz.bm-marked contexts
- GET /_bm/api/v1/materials takes q: candidates are re-gated, counted and
  paged in SQL in rank order, each row with at most one plain snippet
- search failure answers 503 Search is unavailable.; without q the list
  is unchanged

models/material_search_test.go

@@ -0,0 +1,124 @@
+package models_test
+
+import (
+	"slices"
+	"testing"
+	"time"
+
+	"git.golem15.com/jakub/sm-bm-plugin/models"
+)
+
+func TestMaterialSearchSchema(t *testing.T) {
+	m := models.Material{}
+	if got := m.SearchableAs(); got != "jz_bm_materials" {
+		t.Errorf("SearchableAs = %q, want jz_bm_materials", got)
+	}
+	fields, ok := m.SearchIndexSchema()["fields"].([]map[string]any)
+	if !ok || len(fields) == 0 {
+		t.Fatalf("schema fields = %#v", m.SearchIndexSchema()["fields"])
+	}
+	byName := map[string]map[string]any{}
+	for _, f := range fields {
+		name, _ := f["name"].(string)
+		typ, _ := f["type"].(string)
+		if name == "" || typ == "" {
+			t.Errorf("field without a name or type: %v", f)
+		}
+		if _, ok := f["locale"]; ok {
+			t.Errorf("field %s sets a locale; the default one folds Polish diacritics", name)
+		}
+		if store, ok := f["store"]; ok && store == false {
+			t.Errorf("field %s turns storage off", name)
+		}
+		byName[name] = f
+	}
+	for _, name := range []string{"body", "file_texts"} {
+		f, ok := byName[name]
+		if !ok {
+			t.Errorf("schema has no %s field", name)
+			continue
+		}
+		if f["optional"] != true {
+			t.Errorf("%s is not optional", name)
+		}
+	}
+	if byName["body"]["type"] != "string" || byName["file_texts"]["type"] != "string[]" {
+		t.Errorf("body %v, file_texts %v: want string and string[]", byName["body"]["type"], byName["file_texts"]["type"])
+	}
+	for _, name := range []string{"id", "title", "source", "url", "tags", "tag_slugs", "course", "course_id", "meeting_id", "meeting_number", "type", "published_at"} {
+		if _, ok := byName[name]; !ok {
+			t.Errorf("schema has no %s field", name)
+		}
+	}
+	if !(&m).ShouldBeSearchable() {
+		t.Error("a material is not searchable")
+	}
+	var nilMaterial *models.Material
+	if nilMaterial.ShouldBeSearchable() {
+		t.Error("a nil material is searchable")
+	}
+}
+
+func TestMaterialDocument(t *testing.T) {
+	plain := models.MaterialPlainBody("# Nagłówek\n\nTekst **pogrubienie** i _kursywa_ oraz [tekst](https://x) i ![obraz](a.png).\n\n> cytat\n> dalej\n\n- punkt `kod` snake_case")
+	want := "Nagłówek Tekst pogrubienie i kursywa oraz tekst i obraz. cytat dalej punkt kod snake_case"
+	if plain != want {
+		t.Errorf("MaterialPlainBody =\n%q\nwant\n%q", plain, want)
+	}
+
+	code := "BM-12"
+	course := &models.Course{ID: 4, Name: "Bezpieczeństwo", Code: &code}
+	courseID, meetingID := uint(4), uint(9)
+	at := time.Date(2026, 10, 6, 10, 0, 0, 0, time.UTC)
+	body := "## Wstęp\n\n**Globalizacja** w praktyce"
+	source := "Giddens"
+	m := models.Material{ID: 12, Title: "Globalizacja", Type: "notatka", CourseID: &courseID, MeetingID: &meetingID, PublishedAt: &at, Body: &body, Source: &source}
+	tags := []models.Tag{{Name: "Globalizacja", Slug: "globalizacja"}, {Name: "Polityka", Slug: "polityka"}}
+	doc := models.MaterialDocument(m, course, 3, tags, []string{"tekst pliku"})
+	checks := map[string]any{
+		"id":             "12",
+		"title":          "Globalizacja",
+		"type":           "notatka",
+		"source":         "Giddens",
+		"course":         "Bezpieczeństwo BM-12",
+		"course_id":      int64(4),
+		"meeting_id":     int64(9),
+		"meeting_number": 3,
+		"published_at":   at.Unix(),
+		"body":           "Wstęp Globalizacja w praktyce",
+	}
+	for k, v := range checks {
+		if doc[k] != v {
+			t.Errorf("doc[%s] = %#v, want %#v", k, doc[k], v)
+		}
+	}
+	if got, _ := doc["tags"].([]string); !slices.Equal(got, []string{"Globalizacja", "Polityka"}) {
+		t.Errorf("tags = %v", doc["tags"])
+	}
+	if got, _ := doc["tag_slugs"].([]string); !slices.Equal(got, []string{"globalizacja", "polityka"}) {
+		t.Errorf("tag_slugs = %v", doc["tag_slugs"])
+	}
+	if got, _ := doc["file_texts"].([]string); !slices.Equal(got, []string{"tekst pliku"}) {
+		t.Errorf("file_texts = %v", doc["file_texts"])
+	}
+
+	// No code, no course id, no meeting, a draft, no files.
+	bare := models.MaterialDocument(models.Material{ID: 5, Title: "Szkic", Type: "inne"}, &models.Course{Name: "Teoria"}, 0, nil, nil)
+	if bare["course"] != "Teoria" {
+		t.Errorf("course without code = %v", bare["course"])
+	}
+	for _, k := range []string{"course_id", "meeting_id", "published_at"} {
+		if bare[k] != int64(0) {
+			t.Errorf("bare %s = %#v, want 0", k, bare[k])
+		}
+	}
+	for _, k := range []string{"meeting_number", "file_texts", "body", "source", "url"} {
+		if _, ok := bare[k]; ok {
+			t.Errorf("bare document carries %s", k)
+		}
+	}
+	none := models.MaterialDocument(models.Material{ID: 6, Title: "X", Type: "link"}, nil, 0, nil, nil)
+	if _, ok := none["course"]; ok {
+		t.Error("a material without a course carries course")
+	}
+}