feat(extraction): C# property extraction with HAS_PROPERTY edges

Extracts property_declaration, indexer_declaration, event_declaration, and
event_field_declaration from C# class bodies as 'Property' label nodes.
Previously these were completely invisible to the knowledge graph.

Creates HAS_PROPERTY edges from Class → Property in both parallel and serial
indexing paths (pass_parallel.c, pass_definitions.c).

Extracted metadata: property name, qualified name, file path, line range,
declared type (from type field), decorators, export status.

Tested: C# monolith (26K nodes) gained 3,470 Property nodes and 6,943 new
edges including HAS_PROPERTY. trace_call_path now shows 5 properties for
a typical service class.

Author: Your Name

internal/cbm/extract_defs.c

@@ -1810,6 +1810,61 @@ static void extract_class_methods(CBMExtractCtx *ctx, TSNode class_node, const c
             continue;
         }
 
+        /* C#/Java property extraction: property_declaration, auto_property_declaration.
+         * Creates a "Property" node with parent_class set for DEFINES_METHOD edge. */
+        const char *child_type = ts_node_type(child);
+        if (child_type &&
+            (strcmp(child_type, "property_declaration") == 0 ||
+             strcmp(child_type, "indexer_declaration") == 0 ||
+             strcmp(child_type, "event_declaration") == 0 ||
+             strcmp(child_type, "event_field_declaration") == 0)) {
+            TSNode name_node = ts_node_child_by_field_name(child, "name", 4);
+            if (ts_node_is_null(name_node)) {
+                /* indexer_declaration doesn't have a 'name' field, use "this" */
+                if (strcmp(child_type, "indexer_declaration") == 0) {
+                    CBMDefinition pdef;
+                    memset(&pdef, 0, sizeof(pdef));
+                    pdef.name = cbm_arena_strdup(ctx->arena, "this[]");
+                    pdef.qualified_name = cbm_arena_sprintf(ctx->arena, "%s.this[]", class_qn);
+                    pdef.label = "Property";
+                    pdef.file_path = ctx->rel_path;
+                    pdef.parent_class = class_qn;
+                    pdef.start_line = ts_node_start_point(child).row + 1;
+                    pdef.end_line = ts_node_end_point(child).row + 1;
+                    pdef.lines = (int)(pdef.end_line - pdef.start_line + 1);
+                    TSNode type_node = ts_node_child_by_field_name(child, "type", 4);
+                    if (!ts_node_is_null(type_node)) {
+                        pdef.return_type = cbm_node_text(ctx->arena, type_node, ctx->source);
+                    }
+                    cbm_defs_push(&ctx->result->defs, ctx->arena, pdef);
+                }
+                continue;
+            }
+            char *pname = cbm_node_text(ctx->arena, name_node, ctx->source);
+            if (pname && pname[0]) {
+                CBMDefinition pdef;
+                memset(&pdef, 0, sizeof(pdef));
+                pdef.name = pname;
+                pdef.qualified_name = cbm_arena_sprintf(ctx->arena, "%s.%s", class_qn, pname);
+                pdef.label = "Property";
+                pdef.file_path = ctx->rel_path;
+                pdef.parent_class = class_qn;
+                pdef.start_line = ts_node_start_point(child).row + 1;
+                pdef.end_line = ts_node_end_point(child).row + 1;
+                pdef.lines = (int)(pdef.end_line - pdef.start_line + 1);
+                pdef.is_exported = cbm_is_exported(pname, ctx->language);
+                /* Extract type */
+                TSNode type_node = ts_node_child_by_field_name(child, "type", 4);
+                if (!ts_node_is_null(type_node)) {
+                    pdef.return_type = cbm_node_text(ctx->arena, type_node, ctx->source);
+                }
+                pdef.decorators = extract_decorators(ctx->arena, child, ctx->source,
+                                                     ctx->language, spec);
+                cbm_defs_push(&ctx->result->defs, ctx->arena, pdef);
+            }
+            continue;
+        }
+
         if (!cbm_kind_in_set(child, spec->function_node_types)) {
             continue;
         }

src/pipeline/pass_definitions.c

@@ -271,6 +271,13 @@ int cbm_pipeline_pass_definitions(cbm_pipeline_ctx_t *ctx, const cbm_file_info_t
                     cbm_gbuf_insert_edge(ctx->gbuf, parent->id, node_id, "DEFINES_METHOD", "{}");
                 }
             }
+            /* HAS_PROPERTY edge: Class → Property */
+            if (def->parent_class && def->label && strcmp(def->label, "Property") == 0) {
+                const cbm_gbuf_node_t *parent = cbm_gbuf_find_by_qn(ctx->gbuf, def->parent_class);
+                if (parent && node_id > 0) {
+                    cbm_gbuf_insert_edge(ctx->gbuf, parent->id, node_id, "HAS_PROPERTY", "{}");
+                }
+            }
 
             total_defs++;
         }

src/pipeline/pass_parallel.c

@@ -943,6 +943,14 @@ int cbm_build_registry_from_cache(cbm_pipeline_ctx_t *ctx, const cbm_file_info_t
                                          "{}");
                 }
             }
+            /* HAS_PROPERTY edge: Class → Property */
+            if (def->parent_class && def->label && strcmp(def->label, "Property") == 0) {
+                const cbm_gbuf_node_t *parent = cbm_gbuf_find_by_qn(ctx->gbuf, def->parent_class);
+                if (parent && def_node) {
+                    cbm_gbuf_insert_edge(ctx->gbuf, parent->id, def_node->id, "HAS_PROPERTY",
+                                         "{}");
+                }
+            }
         }
 
         /* IMPORTS edges */