chore: establish clean v0.2 baseline

Include only the working reconstruction prototype with Ollama integration:
- double-wrapping fix (lib/llm/provider.js)
- explicit v0.2 JSON output schema (prompts/reconstruct-v0.2.md)
- Zod validation layer (lib/reconstruction/schema.js)
- shared core analysis path (lib/analysis.js)
- prompt versioning infrastructure (lib/reconstruction/prompt.js)
- provider abstraction
- functioning Ollama provider path
- updated API route with centralized analysis
- UI components displaying v0.2 data and validation errors
- .gitignore rules for generated evaluation artifacts

Exclude: evaluator experiments, diagnostic tests, debug scripts,
generated artifacts, comparison findings, test data tied to evaluator.

lib/reconstruction/prompt.js

@@ -1,5 +1,17 @@
-export function buildPrompt(scenario) {
-  return `You are a neutral analyst performing an evidence-based reconstruction of the following scenario. 
+import { promises as fs } from "node:fs";
+import { fileURLToPath } from "node:url";
+import { dirname, join } from "node:path";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+const PROMPTS_DIR = join(__dirname, "../../prompts");
+
+/** Available prompt versions */
+export const PROMPT_VERSIONS = ["v0.1", "v0.2"];
+
+/** Build a v0.1 (extraction-only) prompt inline for backward compatibility */
+function buildV1Prompt(scenario) {
+  return `You are a neutral analyst performing an evidence-based reconstruction of the following scenario.
 
 Rules:
 1. Do NOT invent facts. Only include information present in the scenario or clearly implied.
@@ -29,3 +41,38 @@ Return valid JSON matching this structure exactly:
 
 Return ONLY the JSON object. No markdown, no explanation, no preamble.`;
 }
+
+/** Load a versioned prompt from disk and substitute {{SCENARIO}} */
+async function buildV2Prompt(scenario) {
+  try {
+    const content = await fs.readFile(
+      join(PROMPTS_DIR, "reconstruct-v0.2.md"),
+      "utf-8",
+    );
+    return content.replace("{{SCENARIO}}", scenario);
+  } catch {
+    // Fall back to v0.1 prompt if v0.2 file is missing
+    return buildV1Prompt(scenario);
+  }
+}
+
+/**
+ * Build an analysis prompt for the given version.
+ * @param {"v0.1" | "v0.2"} [version="v0.2"]
+ * @returns {Promise<{prompt: string, version: string}>}
+ */
+export async function buildPrompt(scenario, version = "v0.2") {
+  let prompt;
+  switch (version) {
+    case "v0.1":
+      prompt = buildV1Prompt(scenario);
+      break;
+    default: // v0.2
+      prompt = await buildV2Prompt(scenario);
+      break;
+  }
+
+  const strongJsonHint =
+    "\n\nReturn ONLY a valid JSON object starting with { and ending with }. Do NOT include any text before the opening brace or after the closing brace. Do NOT wrap in markdown backticks.";
+  return { prompt: prompt + strongJsonHint, version };
+}