Migrate to SmithDB-backed SDK methods

Migrate this codebase's LangSmith SDK usage to the new SmithDB-backed methods.

Fetch https://docs.langchain.com/langsmith/smithdb-sdk-migration.md first. It
carries the minimum SDK versions, deprecation dates, exception changes, and
discontinued methods that apply to every call site.

The before/after change for each method lives on a per-area page. Fetch the
ones covering the functionality this codebase actually uses:

- Searching the runs in a project (filters, field projection, sorting,
  pagination):
  https://docs.langchain.com/langsmith/smithdb-sdk-migration-query-runs.md
- Fetching one run by ID, loading its child runs, and building the URL of a
  run in the LangSmith UI:
  https://docs.langchain.com/langsmith/smithdb-sdk-migration-runs.md
- Querying the traces in a project, reading their token and cost aggregates,
  and listing the runs in one trace:
  https://docs.langchain.com/langsmith/smithdb-sdk-migration-traces.md
- Querying the threads in a project and listing the traces (turns) in one
  thread:
  https://docs.langchain.com/langsmith/smithdb-sdk-migration-threads.md
- Querying the runs recorded by an experiment on a dataset:
  https://docs.langchain.com/langsmith/smithdb-sdk-migration-experiments.md
- Creating feedback on a run, adding runs to an annotation queue, and
  sharing, unsharing, or reading publicly shared runs:
  https://docs.langchain.com/langsmith/smithdb-sdk-migration-feedback.md

Treat those pages together as the source of truth for what changed, including
which methods and parameters are affected, what replaces them, and deployment
support.

1. Check the installed LangSmith SDK version against the minimum version
   required for the SmithDB-backed methods per this guide, and upgrade the
   dependency if it does not meet that minimum.
2. Identify every call site in this codebase that uses a method the guide
   marks as migrated, in whichever language(s) this codebase uses.
3. For each call site, apply the corresponding before/after change from the
   area page for that method, including any added, removed, or renamed
   parameters.

If a call site or parameter is not covered by the guide, stop and ask rather
than guessing.