feat(batch-agent): add E2E evaluation harness with Langfuse integration

- eval/mock_executor.py: intercepts execute_on_client, serves fixture
  files from disk, records all mutations (insert/update/delete)
- eval/config.py: YAML fixture loader with prompt variants, expected
  results, seed records, model overrides
- eval/scorer.py: FieldMatchScorer (fuzzy title match, per-field
  accuracy, precision/recall/F1) + LLMJudgeScorer (semantic eval)
- eval/langfuse_eval.py: sync fixtures to Langfuse datasets, create
  dataset runs, post scores, link traces to runs
- eval/runner.py: orchestrates fixture → mock → agent pipeline →
  scoring → Langfuse reporting
- eval/cli.py: CLI (python -m eval run/list/sync) with --models,
  --variants, --fixture, --no-judge flags
- eval/fixtures/: example Italian freelance scenario with 3 prompt
  variants (baseline, detailed_italian, minimal)

services/batch-agent/eval/fixtures/freelance_invoices.yaml

@@ -0,0 +1,86 @@
+# Fixture: freelance-invoices
+# Tests extraction of tasks, notes, and timelines from
+# invoices and meeting notes typical of a freelance workflow.
+
+name: freelance-invoices
+description: >
+  Extract tasks, notes, and timeline events from Italian freelance
+  invoices and meeting notes. Tests project matching, priority
+  mapping, and bilingual content handling.
+
+directory: sample_files/invoices
+data_types: [tasks, notes, timelines]
+file_extensions: [txt, md]
+
+# Pre-existing records in the "database"
+seed_records:
+  projects:
+    - id: "proj-web-redesign"
+      name: "Redesign Sito Web Corporate"
+      status: "active"
+      aiSummary: "Corporate website redesign for Studio Architettura Bianchi"
+    - id: "proj-ecommerce"
+      name: "E-Commerce FashionStore"
+      status: "active"
+      aiSummary: "Next.js e-commerce platform for FashionStore srl"
+  tasks: []
+  notes: []
+  timelines: []
+
+# Prompt variations to compare
+prompt_variants:
+  baseline: |
+    Extract action items as tasks and summaries as notes.
+    For timelines, extract any mentioned dates and deadlines.
+    Set isAiSuggested=1 on every record.
+
+  detailed_italian: |
+    Estrai i dati dai file come segue:
+    - TASK: ogni azione da fare, deliverable, o item con scadenza.
+      Mappa "URGENTE" o "ALTA PRIORITÀ" → priority: high.
+      Mappa "media priorità" → priority: medium.
+      Mappa "bassa priorità" → priority: low.
+      Se un item è marcato come "completato" o [x], impostalo status: done.
+      Altrimenti status: todo.
+    - NOTE: riassunti di meeting, decisioni prese, note tecniche.
+      Il titolo deve essere descrittivo. Il content deve includere tutti i dettagli.
+    - TIMELINE: date di scadenza, milestone, meeting futuri.
+      Formato data: timestamp Unix in millisecondi.
+    Imposta sempre isAiSuggested=1.
+
+  minimal: |
+    Extract only high-priority action items as tasks.
+    Ignore notes and timelines unless explicitly marked as important.
+    Set isAiSuggested=1.
+
+# Expected extractions (what the agent SHOULD produce)
+# Only key fields are specified — scorer uses fuzzy matching
+expected:
+  tasks:
+    - title: "Sviluppo frontend React"
+      priority: "high"
+      status: "todo"
+    - title: "Integrazione API backend"
+      priority: "medium"
+      status: "todo"
+    - title: "Testing cross-browser e fix bug responsive"
+      status: "todo"
+    - title: "Preparare wireframe homepage"
+      priority: "high"
+      status: "todo"
+    - title: "Setup progetto Next.js e configurare CI/CD"
+      priority: "medium"
+      status: "todo"
+    - title: "Ricerca plugin Stripe per gestione abbonamenti"
+      priority: "low"
+      status: "todo"
+
+  notes:
+    - title: "Meeting Kickoff Progetto E-Commerce"
+
+  timelines:
+    - title: "MVP E-Commerce pronto"
+    - title: "Meeting di revisione"
+
+# Models to test (can be overridden via CLI --models)
+models: []