feat(writes): expand WRITES detection to all obj.field = value assignments

Previously handle_readwrites only captured this.X = value (requiring the
receiver to be this/base/self). In JS/TS, most state mutations use
obj.field = value where obj is a parameter or local variable:
  filter.captureNodeId = captureNodeIds
  session.recordedFiles = files
  metadata.startTime = clipStartTime

These were invisible to WRITES edge detection.

Fix: remove the this/base/self receiver check from the member_expression
branch. Now extracts the property name from ANY obj.field = value pattern.
The registry resolution step in pass_usages.c filters out names that don't
match any Property/Method node, preventing noise from built-in properties
like x.length or result.data.

Tested on JS repo: WRITES 1 → 14 edges. New edges correctly identify
functions that mutate object state (getUpdaterStatusById → status,
updateSimulatorSessionFileUploadStatus → status).

Requires full reindex.

Author: Your Name

internal/cbm/extract_semantic.c

@@ -275,35 +275,28 @@ void handle_readwrites(CBMExtractCtx *ctx, TSNode node, const CBMLangSpec *spec,
                     cbm_rw_push(&ctx->result->rw, ctx->arena, rw);
                 }
             }
-            /* member_access_expression: handle this.Property = value
-             * for C#, Java, TypeScript, JavaScript.
-             * Extracts the property name when the receiver is "this" or "base". */
+            /* member_access_expression / member_expression: obj.field = value
+             * Captures property writes for ALL receiver types, not just "this".
+             * In JS/TS, state mutations are often obj.field = value where obj is a
+             * parameter or local variable (filter.status, session.recordedFiles).
+             * The extracted property name goes through registry resolution in
+             * pass_usages.c — names that don't match any Property/Method node
+             * are silently dropped, filtering out noise like x.length = 5. */
             else if (strcmp(lk, "member_access_expression") == 0 ||
                      strcmp(lk, "member_expression") == 0) {
-                TSNode expr = ts_node_child_by_field_name(left, "expression", 10);
                 TSNode name_node = ts_node_child_by_field_name(left, "name", 4);
-                /* member_expression (JS/TS) uses "object" + "property" field names */
+                /* member_expression (JS/TS) uses "property" field name */
                 if (ts_node_is_null(name_node)) {
                     name_node = ts_node_child_by_field_name(left, "property", 8);
                 }
-                if (ts_node_is_null(expr)) {
-                    expr = ts_node_child_by_field_name(left, "object", 6);
-                }
-                if (!ts_node_is_null(name_node) && !ts_node_is_null(expr)) {
-                    const char *ek = ts_node_type(expr);
-                    /* Accept: this.X, base.X, self.X (Python) */
-                    if (strcmp(ek, "this_expression") == 0 ||
-                        strcmp(ek, "this") == 0 ||
-                        strcmp(ek, "base_expression") == 0 ||
-                        strcmp(ek, "self") == 0) {
-                        char *name = cbm_node_text(ctx->arena, name_node, ctx->source);
-                        if (name && name[0] && !cbm_is_keyword(name, ctx->language)) {
-                            CBMReadWrite rw;
-                            rw.var_name = name;
-                            rw.is_write = true;
-                            rw.enclosing_func_qn = state->enclosing_func_qn;
-                            cbm_rw_push(&ctx->result->rw, ctx->arena, rw);
-                        }
+                if (!ts_node_is_null(name_node)) {
+                    char *name = cbm_node_text(ctx->arena, name_node, ctx->source);
+                    if (name && name[0] && !cbm_is_keyword(name, ctx->language)) {
+                        CBMReadWrite rw;
+                        rw.var_name = name;
+                        rw.is_write = true;
+                        rw.enclosing_func_qn = state->enclosing_func_qn;
+                        cbm_rw_push(&ctx->result->rw, ctx->arena, rw);
                     }
                 }
             }