refactor(concept-diagrams): rename + tighten v1k22's skill for merge

Salvage of PR #11045 (original by v1k22). Changes on top of the
original commit:

- Rename 'architecture-visualization-svg-diagrams' -> 'concept-diagrams'
  to differentiate from the existing architecture-diagram skill.
  architecture-diagram stays as the dark-themed Cocoon-style option for
  software/infra; concept-diagrams covers physics, chemistry, math,
  engineering, physical objects, and educational visuals.
- Trigger description scoped to actual use cases; removed the 'always
  use this skill' language and long phrase-capture list to stop
  colliding with architecture-diagram, excalidraw, generative-widgets,
  manim-video.
- Default output is now a standalone self-contained HTML file (works
  offline, no server). The preview server is opt-in and no longer part
  of the default workflow.
- When the server IS used: bind to 127.0.0.1 instead of 0.0.0.0 (was a
  LAN exposure hazard on shared networks) and let the OS pick a free
  ephemeral port instead of hard-coding 22223 (collision prone).
- Shrink SKILL.md from 1540 to 353 lines by extracting reusable
  material into linked files:
    - templates/template.html (host page with full CSS design system)
    - references/physical-shape-cookbook.md
    - references/infrastructure-patterns.md
    - references/dashboard-patterns.md
  All 15 examples kept intact.
- Add dhandhalyabhavik@gmail.com -> v1k22 to AUTHOR_MAP.

Preserves v1k22's authorship on the underlying commit.

scripts/release.py

@@ -229,6 +229,7 @@ AUTHOR_MAP = {
     "zaynjarvis@gmail.com": "ZaynJarvis",
     "zhiheng.liu@bytedance.com": "ZaynJarvis",
     "mbelleau@Michels-MacBook-Pro.local": "malaiwah",
+    "dhandhalyabhavik@gmail.com": "v1k22",
 }