feat(registry): mk / yt / hw theme families — 29 items

Adds three themed registry families contributed by @jbernard077:

- mk-*  minimal presentation  (7 blocks, 3 components)
- yt-*  retro-broadcast creator (5 blocks, 4 components)
- hw-*  hand-drawn scribble   (6 blocks, 5 components)

Consolidates PRs #1933, #1992, #1993 and #1994, cuts 5 of the original 34
items, and fixes the defects that CI never got to report.

Cut (5), each covered by something we already ship or trivial to inline:
- yt-doc-lower-third — would be the 12th name/role lower third next to the
  10 lt-* variants and lower-third-bild
- mk-logo-sting — logo-outro exists, and yt-logo-intro is the richer version
- mk-cta-button, mk-pill-callout, yt-avatar-pip — a styled button, a styled
  chip and a masked circle

Fixes:
- hw-path-text rendered as a solid black blob. #hw-pt-path is the textPath
  carrier and had no rule, so it inherited SVG's default black fill while
  only #hw-pt-guide set fill:none.
- mk-line-graph value labels collided with their own dots and each other.
  Series after the first now label downward, and the offset moved off a CSS
  transform because the entrance tween animates y and GSAP rewrote it.
- Added demo.html for the 11 components and the 3 transparent-root blocks.
  Without it generate-catalog-previews.ts skips components entirely, so the
  catalog-previews job failed for every component in the original PRs.
- Tagged hw-title, hw-pipeline and hw-path-text as overlays.

Also registers all catalog pages in docs.json, which the original PRs left
orphaned, and picks up 4 pre-existing blocks that had no catalog page
(camcorder-hud, editorial-flash-overlay, freeze-frame-dressing,
organic-light-leak-overlay) because the regenerated nav now links them.

Every item was verified by rendering it and looking at the frames.

Co-authored-by: jbernard077 <jbernard077@users.noreply.github.com>

registry/blocks/mk-line-graph/mk-line-graph.html

@@ -57,7 +57,11 @@
         letter-spacing: -0.01em;
         color: var(--mk-ink);
         font-variant-numeric: tabular-nums;
-        transform: translate(-50%, -100%);
+        /* Horizontal centring only. The label's vertical offset is baked into
+           `top` instead of a CSS translate, because the entrance tween animates
+           `y` and GSAP rewrites this transform, dropping any vertical shift. */
+        transform: translate(-50%, 0);
+        line-height: 38px;
         white-space: nowrap;
       }
       .mk-lg-xlabel {
@@ -197,11 +201,16 @@
 
             if (CONFIG.showValues) {
               var val = document.createElement("div");
+              /* Series after the first label downward. With every series
+                 labelling upward the numbers collide wherever the lines run
+                 close together. GAP clears the dot radius plus line stroke. */
+              var below = si > 0;
+              var GAP = 22;
               val.className = "mk-lg-value";
               val.id = "mk-lg-val-" + si + "-" + i;
               val.textContent = v;
               val.style.left = px(i) + "px";
-              val.style.top = py(v) - 20 + "px";
+              val.style.top = py(v) + (below ? GAP : -(GAP + 38)) + "px";
               labels.appendChild(val);
               vals.push({ el: val, si: si, i: i });
             }