test(instrument): tier-2 test port for langfuse (port-as-is)

[mmercuri]

Summary

Ports the deeper Langfuse adapter test suite from ateam as-is. The Langfuse adapter is a batch importer/exporter (not a runtime instrumentation adapter), so tests focus on lifecycle, sync semantics, and the REPLAY surface — NOT streaming.

Source: `A:/github/layerlens/ateam/tests/adapters/langfuse/test_lifecycle.py` (232 LOC)
Target: `tests/instrument/adapters/frameworks/langfuse/test_lifecycle.py`
Owning PR: #110 (`feat/instrument-frameworks-langfuse-closure`)

What was ported

22 tests covering:

• Adapter initialization, FRAMEWORK/VERSION constants
• `has_stratix` / `is_connected` flags with and without a STRATIX instance
• `connect()` without config — adapter is usable standalone, status HEALTHY
• `connect()` with config — creates LangfuseAPIClient, runs health check
• `connect()` with failed health check — status DEGRADED
• `connect(config=cfg)` direct-arg path
• `disconnect()` clears client/importer/exporter/sync references
• `health_check()` no-config branch ("No Langfuse config" message)
• `health_check()` connected branch ("reachable" message)
• `get_adapter_info()` capabilities (TRACE_TOOLS, TRACE_MODELS, REPLAY)
• `serialize_for_replay()` — REPLAY surface returns ReplayableTrace with sync_state metadata
• `get_status()` — both empty and configured (host, mode, langfuse_healthy)
• `import_traces()` / `export_traces()` / `sync()` — error semantics when not connected
• `sync_state` and `config` properties

Adjustments (port-as-is — minimal only)

• `from stratix.sdk.python.adapters.base` → `from layerlens.instrument.adapters._base`
• `from stratix.sdk.python.adapters.langfuse.config` → `from layerlens.instrument.adapters.frameworks.langfuse.config`
• `from stratix.sdk.python.adapters.langfuse.lifecycle` → `from layerlens.instrument.adapters.frameworks.langfuse.lifecycle`
• `@patch("stratix.sdk.python.adapters.langfuse.lifecycle.LangfuseAPIClient")` → `@patch("layerlens.instrument.adapters.frameworks.langfuse.lifecycle.LangfuseAPIClient")`

No test bodies, assertions, or semantics were changed. `MockStratix` retained verbatim. No `org_id` kwarg added (PR #118 still draft — base adapter does not yet accept it).

Honest scope (CLAUDE.md item 11)

• All 22 source tests ported. Zero skipped. Zero rewritten.
• No streaming assertions added — Langfuse has no streaming entry point and PR feat(instrument): Langfuse adapter closure — sample + doc + LayerLens alias (lifecycle_preview → mature) #110 honestly excludes STREAMING from its capability declaration. REPLAY surface IS asserted via `test_serialize_for_replay` and `test_serialize_includes_sync_state`.
• Coexists with the existing `tests/instrument/adapters/frameworks/test_langfuse_adapter.py` (12 tests, different stylistic shape) on the closure branch — both files pass together (34/34).

Test plan

• `uv run python -m pytest tests/instrument/adapters/frameworks/langfuse/ -x` — 22/22 pass
• Co-run with existing closure-branch test file — 34/34 pass, no regression
• CI green on PR