feat: port el-ui vessels — rename crates→vessels, add El source + manifests

ui/vessels/el-graph/src/edge.el

@@ -0,0 +1,44 @@
+// edge.el — Edge type definitions and visual encoding.
+//
+// Edges are directed (source -> target) with a weight and optional relation label.
+
+// ── Edge JSON accessors ──────────────────────────────────────────────────────
+//
+// Edges are passed as JSON objects: { source_id, target_id, weight, relation }
+
+fn edge_source(e_json: String) -> String {
+    let s: String = json_get_string(e_json, "source_id")
+    if !str_eq(s, "") { return s }
+    json_get_string(e_json, "source")
+}
+
+fn edge_target(e_json: String) -> String {
+    let t: String = json_get_string(e_json, "target_id")
+    if !str_eq(t, "") { return t }
+    json_get_string(e_json, "target")
+}
+
+fn edge_weight(e_json: String) -> Float {
+    let w: Float = json_get_float(e_json, "weight")
+    if w == int_to_float(0) { return int_to_float(1) }
+    w
+}
+
+fn edge_relation(e_json: String) -> String {
+    json_get_string(e_json, "relation")
+}
+
+// ── Edge visual encoding ─────────────────────────────────────────────────────
+
+// Stroke width clamped to [1, 4] based on weight.
+fn edge_stroke_width(weight: Float) -> Float {
+    let min_w: Float = int_to_float(1)
+    let max_w: Float = int_to_float(4)
+    let range: Float = max_w - min_w
+    let clamped: Float = if weight < min_w { min_w } else { if weight > max_w { max_w } else { weight } }
+    clamped
+}
+
+fn edge_stroke_color() -> String { "#3a4a5a" }
+
+fn edge_stroke_color_highlight() -> String { "#5a7a9a" }