feat: add cfm model and migration (#43)

* custom fe matter migration

* add custom_fe_matter

core/models/custom_frontmatter.go

@@ -0,0 +1,27 @@
+package models
+
+type CustomFronMatter struct {
+	nodeID string
+	key    string
+	value string
+}
+
+func NewCustomFrontMatter(nodeID, key, value string) *CustomFronMatter {
+	return &CustomFronMatter{
+		nodeID: nodeID,
+		key:    key,
+		value: value,
+	}
+}
+
+func (cfm *CustomFronMatter) NodeID() string {
+	return cfm.nodeID
+}
+
+func (cfm *CustomFronMatter) Key() string {
+	return cfm.key
+}
+
+func (cfm *CustomFronMatter) Value() string {
+	return cfm.value
+}

persistence/migrations/004_custom_frontmatter.sql

@@ -0,0 +1,9 @@
+CREATE TABLE custom_frontmatter(
+  note_id TEXT,
+  key TEXT,
+  value TEXT,
+  PRIMARY KEY (note_id, key, value),
+  FOREIGN KEY (note_id) REFERENCES note(id) ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS idx_cfe_key_value on custom_frontmatter(key, value);