feat(article): 正文图片可放大——PhotoZoom 极简 viewer 双轨挂载

正文 .prose-reading/.prose-tech 图片单击唤起全屏 dialog：fit-
contain+滚轮光标锚点缩放 1-5x+拖拽（钳制数学与图库 v2 逐行同
源）+双击 1x↔2.5x+Esc/关闭/背景点击关（contain 内容盒几何判
定）；无 EXIF/caption/FLIP（纯图极简，按契约）；document
委托点击软导航后仍生效。

车道：op-artalk（专项 9/9：SVG 架构图唤起/矢量 2.46x 不栅格化/
拖拽钳制/双击回正/Esc/jpg/背景关/软导航）；收编验收四断言+E2E
34/34 全过

验证: 文章 SVG 点击唤起+滚轮放大（naturalWidth 960 矢量源）+Esc
      关闭实测；E2E 34/34

Spec: none (文章图放大，车道级交付)

Co-authored-by: GLM-5.3

src/components/geek/PhotoZoom.astro

@@ -0,0 +1,165 @@
+---
+// 正文图片缩放视图（文章页）：单图极简——无画廊专属的 EXIF/caption/FLIP/chrome，
+// 只有图 + 关闭钮。缩放引擎与 GalleryPage v2 同源：钳制数学（applyZoom clamp / 回 1 归零）
+// 与 contain 几何判定（img 元素盒铺满 → 背景按内容盒算）逐行对齐，勿另起炉灶。
+---
+
+<dialog id="pz" class="pz" aria-label="图片查看">
+  <img id="pz-img" class="pz-img" alt="" />
+  <button id="pz-close" class="pz-close" type="button" aria-label="关闭（Esc）">
+    <svg viewBox="0 0 24 24" width="18" height="18" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" aria-hidden="true">
+      <path d="M18 6 6 18M6 6l12 12"></path>
+    </svg>
+  </button>
+</dialog>
+
+<style>
+  .pz {
+    inset: 0;
+    width: 100%;
+    height: 100dvh;
+    max-width: none;
+    max-height: none;
+    margin: 0;
+    padding: 0;
+    border: none;
+    border-radius: 0;
+    background: transparent;
+    overflow: hidden; /* 绝不出滚动条：完整可见交给 contain */
+  }
+  .pz::backdrop { background: rgba(8, 10, 14, 0.96); }
+  /* 绝对填满：grid/flex item 的 % 高有 auto 行高循环失效坑（GalleryPage v2 已踩） */
+  .pz-img {
+    position: absolute;
+    inset: 0;
+    width: 100%;
+    height: 100%;
+    object-fit: contain;
+    outline: none;
+    cursor: zoom-in;
+    touch-action: none;
+    will-change: transform;
+  }
+  .pz-img.zoomed { cursor: grab; }
+  .pz-img.grabbing { cursor: grabbing; }
+  .pz-close {
+    position: absolute;
+    top: 16px;
+    right: 16px;
+    z-index: 3;
+    display: grid;
+    place-items: center;
+    width: 40px;
+    height: 40px;
+    border-radius: 50%;
+    border: 1px solid rgba(255, 255, 255, 0.22);
+    background: rgba(20, 24, 30, 0.55);
+    color: #dfe6f3;
+    cursor: pointer;
+    transition: border-color var(--dur) var(--ease);
+  }
+  .pz-close:hover { border-color: rgba(255, 255, 255, 0.5); }
+  /* 正文图给个可点暗示（仅光标，不动版式） */
+  :global(.prose-reading) :global(img),
+  :global(.prose-tech) :global(img) { cursor: zoom-in; }
+</style>
+
+<script>
+  // 单图缩放：与 GalleryPage v2 引擎同源（钳制/锚点/双击语义一致，数学勿分叉）
+  document.addEventListener('astro:page-load', () => {
+    const dlg = document.getElementById('pz') as HTMLDialogElement | null;
+    const img = document.getElementById('pz-img') as HTMLImageElement | null;
+    if (!dlg || !img) return;
+    const reduced = matchMedia('(prefers-reduced-motion: reduce)');
+
+    const zoom = { s: 1, tx: 0, ty: 0 };
+    const applyZoom = () => {
+      // 平移钳制：缩放后图盒不得超出舞台（|t| ≤ 尺寸差/2）——与 GalleryPage 同源数学
+      const mx = Math.max(0, (img.clientWidth * (zoom.s - 1)) / 2);
+      const my = Math.max(0, (img.clientHeight * (zoom.s - 1)) / 2);
+      zoom.tx = Math.min(mx, Math.max(-mx, zoom.tx));
+      zoom.ty = Math.min(my, Math.max(-my, zoom.ty));
+      img.style.transform = zoom.s === 1 ? 'none' : `translate(${zoom.tx}px, ${zoom.ty}px) scale(${zoom.s})`;
+      img.classList.toggle('zoomed', zoom.s !== 1);
+    };
+    const resetZoom = () => { zoom.s = 1; zoom.tx = 0; zoom.ty = 0; applyZoom(); };
+    const zoomAt = (next: number, cx: number, cy: number) => {
+      const rect = img.getBoundingClientRect();
+      const ax = cx - rect.left - rect.width / 2 - zoom.tx;
+      const ay = cy - rect.top - rect.height / 2 - zoom.ty;
+      const k = next / zoom.s;
+      zoom.tx -= ax * (k - 1);
+      zoom.ty -= ay * (k - 1);
+      if (next <= 1) { zoom.s = 1; zoom.tx = 0; zoom.ty = 0; } else { zoom.s = next; }
+      applyZoom();
+    };
+    const containRect = () => {
+      const iw = img.naturalWidth || 1, ih = img.naturalHeight || 1;
+      const k = Math.min(innerWidth / iw, innerHeight / ih);
+      const w = iw * k, h = ih * k;
+      return { left: (innerWidth - w) / 2, top: (innerHeight - h) / 2, width: w, height: h };
+    };
+
+    // 正文图点击唤起（document 委托：软导航换页后依然生効）
+    document.addEventListener('click', (e) => {
+      const t = e.target as HTMLElement;
+      const source = t.closest('.prose-reading img, .prose-tech img') as HTMLImageElement | null;
+      if (!source) return;
+      if (dlg.open) return;
+      e.preventDefault();
+      img.src = source.currentSrc || source.src;
+      img.alt = source.alt || '';
+      resetZoom();
+      dlg.showModal();
+    });
+    document.getElementById('pz-close')?.addEventListener('click', () => dlg.close());
+    dlg.addEventListener('close', resetZoom);
+
+    dlg.addEventListener('wheel', (e) => {
+      if (!dlg.open) return;
+      e.preventDefault(); // 灯箱内滚轮一律缩放（含 Ctrl+滚轮）
+      const factor = Math.exp(-e.deltaY * 0.0015);
+      const next = Math.min(5, Math.max(1, zoom.s * factor));
+      if (next === zoom.s) return;
+      zoomAt(next, e.clientX, e.clientY);
+    }, { passive: false });
+
+    // 拖拽平移（仅放大态）
+    let drag: { x: number; y: number; tx: number; ty: number; moved: boolean } | null = null;
+    img.addEventListener('pointerdown', (e) => {
+      if (zoom.s <= 1) return;
+      e.preventDefault();
+      img.setPointerCapture(e.pointerId);
+      drag = { x: e.clientX, y: e.clientY, tx: zoom.tx, ty: zoom.ty, moved: false };
+      img.classList.add('grabbing');
+    });
+    img.addEventListener('pointermove', (e) => {
+      if (!drag) return;
+      const dx = e.clientX - drag.x, dy = e.clientY - drag.y;
+      if (Math.abs(dx) + Math.abs(dy) > 3) drag.moved = true;
+      zoom.tx = drag.tx + dx;
+      zoom.ty = drag.ty + dy;
+      applyZoom();
+    });
+    const endDrag = () => { drag = null; img.classList.remove('grabbing'); };
+    img.addEventListener('pointerup', endDrag);
+    img.addEventListener('pointercancel', endDrag);
+    img.addEventListener('dblclick', (e) => {
+      if (zoom.s === 1) zoomAt(2.5, e.clientX, e.clientY);
+      else resetZoom();
+    });
+    // 背景点击关：contain 下 img 盒铺满视口，按内容盒几何判定（GalleryPage v2 结论）
+    dlg.addEventListener('click', (e) => {
+      if (!dlg.open) return;
+      if ((e.target as Element).closest('button')) return;
+      if (drag?.moved) return;
+      const c = containRect();
+      const inside =
+        e.clientX >= c.left - 8 && e.clientX <= c.left + c.width + 8 &&
+        e.clientY >= c.top - 8 && e.clientY <= c.top + c.height + 8;
+      if (!inside) dlg.close();
+    });
+    // reduced-motion：无过渡（本组件只用 transform 直接赋值，本无动画；此守卫留给未来）
+    void reduced;
+  });
+</script>

src/pages/archives/[...slug].astro

@@ -1,6 +1,7 @@
 ---
 import type { CollectionEntry } from 'astro:content';
 import { getCollection, render } from 'astro:content';
+import PhotoZoom from '../../components/geek/PhotoZoom.astro';
 import BaseLayout from '../../layouts/BaseLayout.astro';
 import ArtalkComments from '../../components/ArtalkComments.astro';
 import { trackOf } from '../../content.config';
@@ -116,6 +117,7 @@ const toc = headings.filter((h) => h.depth === 2 || h.depth === 3);
   </nav>
 
   <ArtalkComments pageKey={`/archives/${entry.id}/`} pageTitle={entry.data.title} />
+  <PhotoZoom />
 </BaseLayout>
 
 <script>

src/pages/en/archives/[...slug].astro

@@ -2,6 +2,7 @@
 // /en/archives/{slug}：英文版文章页——postsEn 优先；缺译回退 zh 正文 + 醒目标注
 import type { CollectionEntry } from 'astro:content';
 import { getCollection, render } from 'astro:content';
+import PhotoZoom from '../../../components/geek/PhotoZoom.astro';
 import BaseLayout from '../../../layouts/BaseLayout.astro';
 import ArtalkComments from '../../../components/ArtalkComments.astro';
 import AiTranslatedBadge from '../../../components/AiTranslatedBadge.astro';
@@ -67,6 +68,7 @@ const minutes = Math.max(1, Math.ceil(words / 220));
     </nav>
     <ArtalkComments pageKey={`/archives/${entry.id}/`} pageTitle={entry.data.title} />
   </article>
+  <PhotoZoom />
 </BaseLayout>
 
 <style>