feat: add manual export provider and ReviewRequest pattern

Implement Task 8.0 — Manual Export Provider with full provider abstraction:

Source files:
- src/providers/manual-export.js (104 lines) — new provider that wraps
  pre-built prompts in copy-ready format for ChatGPT Web/Business use
- src/providers/factory.js — register 'manual' provider in whitelist
- src/providers/openai.js — update JSDoc for ProviderRequest parameter

All 5 handlers updated with ReviewRequest pattern:
- src/tools/ask-chatgpt.js
- src/tools/debug-issue.js
- src/tools/review-code.js
- src/tools/review-plan.js
- src/tools/architecture-review.js
Each handler now packages shared data as { prompt, input } between step 5
and 6 of the orchestration flow.

Tests:
- test/providers/manual-export.test.js (56 tests) — covers structure,
  copy-ready box formatting, tool name detection, long prompts, Unicode,
  edge cases, provider contract compliance, idempotency
- test/providers/factory.test.js (+9 tests) — manual provider whitelist,
  factory routing, send delegation

Docs:
- ARCHITECTURE.md — provider selection table with openai/manual values
- README.md — provider comparison table and manual workflow description

src/tools/review-code.js

@@ -15,7 +15,8 @@ import { buildReviewCodePrompt } from "../prompts/review-code.js";
  *   Raw tool input per ARCHITECTURE.md §7 schema.
  * @param {{
  *   loadConfig: () => object,
- *   createProvider: (config: object) => { send: (input: object, cfg: object) => Promise<{ content: string }> }
+ *   createProvider: (config: object) => { send: (request: ProviderRequest, cfg: object) => Promise<{ content: string }> }
+ *     ProviderRequest = { prompt?: string, input?: object }
  * }} deps
  *   Injected external dependencies.
  * @returns {Promise<{ ok: true, answer: string, warnings: string[] } | { ok: false, error: string, warnings: string[] }>}
@@ -57,11 +58,15 @@ export async function handleReviewCode(input, deps) {
     return { ok: false, error: String(err), warnings: [] };
   }
 
+  // --- 5b. Package shared data for provider ---
+
+  const reviewRequest = { prompt: promptMessages, input: budget.input };
+
   // --- 6. Send via provider ---
 
   let aiResult;
   try {
-    aiResult = await provider.send(budget.input, config);
+    aiResult = await provider.send(reviewRequest, config);
   } catch (err) {
     return { ok: false, error: String(err), warnings: [] };
   }