fix(langfuse): remove invalid user_id/session_id kwargs from start_as_current_observation

Langfuse V3 does not accept user_id/session_id on observation-level calls.
Moved to metadata dict in agent_runner, deep_agent, and agent_setup.

refactor(tests): fixture-based pattern for agent_runner_v2 eval tests

- cases.yaml + data/ fixtures under tests/fixtures/agent_runner_v2/
- pytest_generate_tests parametrizes test_eval_runner from YAML
- _resolve_projects() handles symbolic names and inline dicts
- _evaluate_case() centralizes all assertion logic
- --runner-dir CLI option for custom fixture folders

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/fixtures/agent_runner_v2/cases.yaml

@@ -0,0 +1,86 @@
+# Agent Runner V2 — eval test cases (Step 2, requires real LLM)
+#
+# Each case drives one parametrized `test_eval_runner` invocation.
+#
+# Keys
+# ----
+# id: str                     unique identifier shown in pytest output
+# description: str            human-readable label
+# file: str                   filename inside data/
+# file_path: str              path reported to the executor (affects project-matching via filename)
+# projects: [alpha|beta]      symbolic project names resolved by the test helper
+#
+# Optional pre-existing records (dedup tests)
+# existing_tasks:             list of {id, title, status, priority}
+# existing_notes:             list of {id, title, content}
+# existing_timelines:         list of {id, title, date}
+#
+# Assertions (one or more)
+# expect_insert: <table>      at least 1 insert row in this table (tasks|notes|timelines)
+# expect_no_insert: true      zero inserts in any table
+# expect_project_id: <id>     any insert must carry this projectId
+# expect_dedup: true          task inserts == 0 OR task updates >= 1 (dedup check)
+#
+# Langfuse
+# score_name: str             observation score name
+
+- id: "2.1"
+  description: "Action email → create_task"
+  file: email_action.html
+  file_path: /emails/ProjectAlpha_action.html
+  projects: [alpha, beta]
+  expect_insert: tasks
+  score_name: runner.email_to_task
+
+- id: "2.2"
+  description: "Informational email → create_note"
+  file: email_info.html
+  file_path: /emails/ProjectAlpha_info.html
+  projects: [alpha, beta]
+  expect_insert: notes
+  score_name: runner.email_to_note
+
+- id: "2.3"
+  description: "Email with meeting date → create_timeline"
+  file: email_date.html
+  file_path: /emails/ProjectAlpha_kickoff.html
+  projects: [alpha, beta]
+  expect_insert: timelines
+  score_name: runner.email_to_timeline
+
+- id: "2.4"
+  description: "Filename contains project name → correct project assigned"
+  file: email_action.html
+  file_path: /emails/ProjectAlpha_report.html
+  projects: [alpha, beta]
+  expect_project_id: proj-alpha
+  score_name: runner.project_filename
+
+- id: "2.5"
+  description: "Email body mentions project → correct project assigned"
+  file: email_action.html
+  file_path: /emails/email_001.html
+  projects: [alpha, beta]
+  expect_project_id: proj-alpha
+  score_name: runner.project_content
+
+- id: "2.6"
+  description: "Newsletter + global rule no-project → no creates"
+  file: email_no_project.html
+  file_path: /emails/newsletter.html
+  projects: [alpha, beta]
+  expect_no_insert: true
+  score_name: runner.no_project
+
+- id: "2.7"
+  description: "Existing task with same title → dedup (update not create)"
+  file: email_action.html
+  file_path: /emails/ProjectAlpha_followup.html
+  projects: [alpha]
+  existing_tasks:
+    - id: task-existing
+      title: Fix the login bug
+      status: todo
+      priority: medium
+  expect_dedup: true
+  score_name: runner.dedup