feat(cnn_v3/tools): embed default weights in HTML tool; add --html export flag

- cnn_v3/tools/weights.js: new file — base64-encoded cnn_v3_weights.bin +
  cnn_v3_film_mlp.bin; loaded at startup so the tool works without dropping files
- tester.js: preload() falls back to embedded weights.js constants when fetch
  fails; logs "Loaded embedded" vs "Preloaded" to distinguish the two paths
- index.html: load weights.js before tester.js
- export_cnn_v3_weights.py: add --html / --html-output flags that call
  update_weights_js() to regenerate weights.js after a training run
- HOW_TO_CNN.md: update pipeline diagram, §3 export commands, §7 HTML tool
  section (file table, workflow, weights.js description), Appendix A

handoff(Gemini): weights.js now the canonical source for HTML tool defaults;
regenerate with `uv run export_cnn_v3_weights.py <ckpt> --output ... --html`

1 files changed, 25 insertions, 20 deletions

diff --git a/cnn_v3/tools/tester.js b/cnn_v3/tools/tester.js
index 0412cae..81c869d 100644
--- a/cnn_v3/tools/tester.js
+++ b/cnn_v3/tools/tester.js
@@ -52,29 +52,34 @@ class CNNv3Tester {
   async preload() {
     const base = '../../workspaces/main/weights/';
     const files = [
-      {url: base+'cnn_v3_weights.bin',  isFilm: false},
-      {url: base+'cnn_v3_film_mlp.bin', isFilm: true},
+      {url: base+'cnn_v3_weights.bin',  isFilm: false, b64: CNN_V3_WEIGHTS_B64},
+      {url: base+'cnn_v3_film_mlp.bin', isFilm: true,  b64: CNN_V3_FILM_MLP_B64},
     ];
-    for (const {url, isFilm} of files) {
+    for (const {url, isFilm, b64} of files) {
+      let buf = null;
+      const name = url.split('/').pop();
       try {
         const r = await fetch(url);
-        if (!r.ok) { this.log(`preload skip: ${url.split('/').pop()} (${r.status})`); continue; }
-        const buf = await r.arrayBuffer();
-        const name = url.split('/').pop();
-        if (isFilm) {
-          this.filmMlp = this.parseFilm(buf);
-          const el = document.getElementById('fDrop');
-          el.textContent = `✓ ${name}`; el.classList.add('ok');
-          document.getElementById('fSt').textContent = 'FiLM MLP loaded';
-          document.getElementById('fSt').style.color = '#28a745';
-        } else {
-          this.weightsU32 = this.parseWeights(buf); this.weightsBuffer = buf;
-          if (this.weightsGPU) { this.weightsGPU.destroy(); this.weightsGPU = null; }
-          const el = document.getElementById('wDrop');
-          el.textContent = `✓ ${name}`; el.classList.add('ok');
-        }
-        this.log(`Preloaded: ${name}`);
-      } catch(e) { this.log(`preload error (${url.split('/').pop()}): ${e.message}`, 'err'); }
+        if (r.ok) { buf = await r.arrayBuffer(); this.log(`Preloaded: ${name}`); }
+      } catch(_) {}
+      if (!buf) {
+        const s = atob(b64); const u = new Uint8Array(s.length);
+        for (let i = 0; i < s.length; i++) u[i] = s.charCodeAt(i);
+        buf = u.buffer;
+        this.log(`Loaded embedded: ${name}`);
+      }
+      if (isFilm) {
+        this.filmMlp = this.parseFilm(buf);
+        const el = document.getElementById('fDrop');
+        el.textContent = `✓ ${name}`; el.classList.add('ok');
+        document.getElementById('fSt').textContent = 'FiLM MLP loaded';
+        document.getElementById('fSt').style.color = '#28a745';
+      } else {
+        this.weightsU32 = this.parseWeights(buf); this.weightsBuffer = buf;
+        if (this.weightsGPU) { this.weightsGPU.destroy(); this.weightsGPU = null; }
+        const el = document.getElementById('wDrop');
+        el.textContent = `✓ ${name}`; el.classList.add('ok');
+      }
     }
     if (this.weightsU32) {
       if (this.image || this.isVideo) this.run();