feat(model-profiles): wrap multi-provider build_summary output in <details> toggles (#38664)

`build_summary` in `langchain_model_profiles._summary` now wraps each
provider section in a `<details>` toggle when more than one provider has
changes, making multi-provider refresh PR summaries skimmable.
Single-provider summaries are unchanged.

---

When the `refresh_model_profiles` workflow refreshes data for multiple
partner integrations at once, the resulting PR summary can be long and
hard to skim — every provider's added/removed/changed rows are rendered
flat, one after another. This wraps each provider section in a
`<details>`/`<summary>` toggle when more than one provider has changes,
so reviewers can expand only the providers they care about.
Single-provider summaries stay flat since there's nothing to collapse.

The per-provider `### {provider}` heading is stripped inside toggles so
the `<summary>` tag is the sole label — no duplicated provider name.

Also includes two smaller changes that were staged alongside:

- The `refresh_model_profiles` and `_refresh_model_profiles` workflow
PR-body templates now link to the workflow file instead of bare-text
referencing it.
- `AGENTS.md` and `CLAUDE.md` document the LangSmith integration test
tracing setup: the env vars CI sets, the pytest plugin that bridges
`LANGSMITH_TAGS`/`LANGSMITH_METADATA` into `tracing_context`, and the
unit-test isolation approach.

---------

Signed-off-by: Mason Daugherty <github@mdrxy.com>
Co-authored-by: open-swe[bot] <215916821+open-swe[bot]@users.noreply.github.com>

.github/workflows/_refresh_model_profiles.yml

@@ -69,7 +69,7 @@ on:
         default: |
           Automated refresh of model profile data via `langchain-profiles refresh`.
 
-          🤖 Generated by the `refresh_model_profiles` workflow.
+          🤖 Generated by the [`refresh_model_profiles` workflow](https://github.com/langchain-ai/langchain/blob/master/.github/workflows/refresh_model_profiles.yml).
       pr-labels:
         description: "Comma-separated labels to apply to the PR."
         required: false

.github/workflows/refresh_model_profiles.yml

@@ -37,10 +37,9 @@ jobs:
       cli-path: libs/model-profiles
       add-paths: libs/partners/**/data/_profiles.py
       pr-body: |
-        Automated refresh of model profile data for all in-monorepo partner
-        integrations via `langchain-profiles refresh`.
+        Automated refresh of model profile data for all in-monorepo partner integrations via `langchain-profiles refresh`.
 
-        🤖 Generated by the `refresh_model_profiles` workflow.
+        🤖 Generated by the [`refresh_model_profiles` workflow](https://github.com/langchain-ai/langchain/blob/master/.github/workflows/refresh_model_profiles.yml).
     secrets:
       MODEL_PROFILE_BOT_CLIENT_ID: ${{ secrets.MODEL_PROFILE_BOT_CLIENT_ID }}
       MODEL_PROFILE_BOT_PRIVATE_KEY: ${{ secrets.MODEL_PROFILE_BOT_PRIVATE_KEY }}