chore(spec): record the five new exports in the public API surface snapshot

`check:api-surface` gates `@objectstack/spec`'s public exports against a checked-in
snapshot. The expression-slot ledger adds five — `FLOW_NODE_EXPRESSION_PATHS`,
`FlowNodeExpressionPath`, `FlowNodeExpressionRole`, `ResolvedFlowNodeExpression`
and `resolveFlowNodeExpressions` — so the snapshot needed regenerating.

Additive only: 0 breaking (nothing removed or narrowed), 5 added. `+5` lines and
nothing else changed.

Every step of the `TypeScript Type Check` job now passes locally: spec `tsc
--noEmit`, `check:docs`, `check:skill-refs`, `check:react-blocks`, the workspace
build, examples typecheck, downstream-contract typecheck, `check:api-surface` and
`check:skill-examples` — plus the other six spec `check:*` gates.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QoA8AV99Ss1RRkLLAYmDzq

Author: claude

packages/spec/api-surface.json

@@ -2090,13 +2090,16 @@
     "ExecutionStepLogParsed (type)",
     "ExecutionStepLogSchema (const)",
     "FLOW_BUILTIN_NODE_TYPES (const)",
+    "FLOW_NODE_EXPRESSION_PATHS (const)",
     "FLOW_STRUCTURAL_NODE_TYPES (const)",
     "Flow (type)",
     "FlowEdge (type)",
     "FlowEdgeParsed (type)",
     "FlowEdgeSchema (const)",
     "FlowNode (type)",
     "FlowNodeAction (const)",
+    "FlowNodeExpressionPath (interface)",
+    "FlowNodeExpressionRole (type)",
     "FlowNodeParsed (type)",
     "FlowNodeSchema (const)",
     "FlowParsed (type)",
@@ -2133,6 +2136,7 @@
     "ParallelConfigParsed (type)",
     "ParallelConfigSchema (const)",
     "RegionAnalysis (interface)",
+    "ResolvedFlowNodeExpression (interface)",
     "RetryPolicy (type)",
     "RetryPolicySchema (const)",
     "ScheduleState (type)",
@@ -2187,6 +2191,7 @@
     "getApprovalNodeConfigJsonSchema (function)",
     "importBpmnToConstructs (function)",
     "normalizeDecisionOutputs (function)",
+    "resolveFlowNodeExpressions (function)",
     "validateControlFlow (function)"
   ],
   "./api": [