fix: update @langchain/core and resolve type compatibility issues

[gfargo]

Summary

Fixes 3 failing test suites (commit.test.ts, conventionalCommitsHandler.test.ts, recap.test.ts) and resolves build failures caused by a @langchain/core version mismatch.

Root Cause

@langchain/classic (transitive dep via @langchain/community) ships a nested @langchain/openai@1.2.13 that requires @langchain/core/utils/standard_schema. This module was introduced in @langchain/core@1.1.32, but the lockfile had pinned @langchain/core to 1.1.24.

Upgrading @langchain/core to 1.1.34 resolved the missing module, but introduced TS2589 "type instantiation is excessively deep" errors — the new StructuredOutputParser types trigger infinite recursion with Zod generics during Rollup's stricter TypeScript compilation.

Changes

1. Updated @langchain/core from 1.1.24 → 1.1.34 (lockfile update)
2. Added targeted type casts to break the recursive type chain:
   • src/lib/langchain/utils/createSchemaParser.ts — return type + fromZodSchema call
   • src/lib/langchain/utils/executeChain.ts — parser type widened to Runnable, result cast
   • src/lib/langchain/utils/executeChainWithSchema.ts — parser variable cast
   • src/commands/changelog/handler.ts — parser cast + explicit executeChain type param
   • src/commands/recap/handler.ts — parser cast + explicit executeChain type param
   • src/commands/review/handler.ts — parser cast

Test Results

Test Suites: 43 passed, 43 total
Tests:       345 passed, 345 total

Build: ✅ dist/index.esm.mjs, dist/index.js created
Lint: ✅ clean