LLM refine: 2dp prompt, mixed 64/32 frames, full proxy log, low reasoning

- spec.js: round all songSpec + extended summary/tempo/normalization to
  r2 (2dp) so high-precision 0.6607… stops wasting tokens; hoist r2/r3
  above specForPrompt to fix ReferenceError; FULL control wording kept.
- thumbs.js: border detection — first/last + 0.5s of any section start
  → 64×64 (borders), interior → 32×32 (between). Back-compat shim for
  old {size:N} callers. Returns size+role per frame for attachFrames.
- vite.config.js: raise sanitizeBodyForLog to 64k for __llm so 8×
  vision frames aren't truncated (was 16384, only 2 images logged).
  Also log reasoningEffort via providerOptions.
- llmTweak.js: set providerOptions reasoningEffort:'low' for both
  streamObject and generateObject fallback to cut 2459 → faster
  streaming progress, temperature 0.7 kept for variety.

Verification: build+lint:scenes green, tests 18/18.

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

flow-state/vite.config.js

@@ -118,19 +118,20 @@ function llmGatewayProxy() {
     }
 
     function sanitizeBodyForLog(ct, raw) {
-        // Don't log if content-type is missing or body is binary
+        // Allow __llm JSON (which includes images) to be larger — spec asked
+        // for full logging. 64k keeps 8× images plus schema without truncation.
+        const limit = 65536;
         if (!ct || !ct.includes('json')) {
-            if (raw && raw.length > 4096) return `[${ct || 'unknown'} body ${raw.length} bytes, not logged]`;
-            try { return raw ? raw.toString('utf8').slice(0, 4096) : ''; } catch { return '[unprintable]'; }
+            if (raw && raw.length > limit) return `[${ct || 'unknown'} body ${raw.length} bytes, not logged]`;
+            try { return raw ? raw.toString('utf8').slice(0, limit) : ''; } catch { return '[unprintable]'; }
         }
         try {
             const text = raw ? raw.toString('utf8') : '';
             const parsed = JSON.parse(text);
-            // Redact sensitive keys if they somehow appear in JSON body
             const redacted = redactJsonForLog(parsed);
-            return JSON.stringify(redacted).slice(0, 16384);
+            return JSON.stringify(redacted).slice(0, limit);
         } catch {
-            return raw ? raw.toString('utf8').slice(0, 4096) : '';
+            return raw ? raw.toString('utf8').slice(0, limit) : '';
         }
     }