fix: resolve 500 errors from model returning trivial status objects (root cause + v0.2 prompt fix)

Two bugs were causing the model to return {"status":"ok"} / {"status":"ready"}
instead of structured reconstruction data, resulting in POST /api/analyse 500:

1. DOUBLE-WRAPPING BUG (lib/llm/provider.js):
   generateReconstruction() called buildPrompt(scenario) on input that was
   already a fully-built prompt string from analyseScenario(). This wrapped the
   v0.1 prompt (~5000+ chars) in another template layer, producing incomprehensible
   output that the model could not parse as structured JSON.
   Fix: Pass scenario through directly (it is ALREADY a built prompt).

2. MISSING JSON SPEC (prompts/reconstruct-v0.2.md):
   The v0.2 prompt template said 'matching the structure exactly' but never
   defined what that structure was. The model invented its own field names
   (input_classification, reasoning_mode, anchors) with snake_case instead of
   camelCase, which failed Zod validation -> 500 errors.
   Fix: Added explicit JSON schema section with exact key names, enum values,
   and nested structure matching the Zod validation layer.

Additionally:
- Refactored route to use analyseScenario from lib/analysis (centralized)
- Added lib/analysis.js with shared analysis logic
- Updated components to display promptVersion and validation errors
- Added lib/reconstruction/prompt.js v0.1/v0.2 versioning
- Added lib/reconstruction/schema.js v0.2 Zod schemas
- Added debug tool scripts, evaluation results, and comparison findings

evaluation-results/2026-08-01T06-01-56/diag-01-result.json

@@ -0,0 +1,56 @@
+{
+  "id": "diag-01",
+  "description": "Baseline comparison — change without context. Should NOT jump to conclusions about quality or staff issues.",
+  "input": "We've seen a spike in complaints from our warehouse team this month compared to last month.",
+  "responseDurationMs": 6,
+  "actualPrimaryType": "unexplained_change",
+  "actualReasoningModes": [
+    "establish_baseline",
+    "identify_difference"
+  ],
+  "technical": {
+    "schemaValid": true,
+    "classificationMatch": true,
+    "reasoningModeMatch": true,
+    "nextQuestionPresent": true,
+    "pass": true,
+    "errors": []
+  },
+  "reasoningQuality": {
+    "requiredConcepts": {
+      "pass": false,
+      "details": [
+        {
+          "concept": "complaints",
+          "found": true
+        },
+        {
+          "concept": "warehouse",
+          "found": false
+        },
+        {
+          "concept": "baseline comparison",
+          "found": false
+        }
+      ]
+    },
+    "unsupportedInferencesAbsent": {
+      "pass": true,
+      "details": [
+        {
+          "concept": "quality issue",
+          "absent": true
+        },
+        {
+          "concept": "staff turnover",
+          "absent": true
+        },
+        {
+          "concept": "training gap",
+          "absent": true
+        }
+      ]
+    },
+    "pass": false
+  }
+}