feat(tasks-ui): readability pass, height-budget fix and leftover sweep

The native port is finished off with the readability work the earlier rounds
left open, plus the cleanup of everything the shadcn era or the older canvas
left behind.

- Geometry: node height is now composed from named parts (chrome, two title
  lines, meta row) and per-node extras, so a teammate card that carries a task
  line no longer gets clipped by the old fixed 68px budget; the layout spec
  follows the new model and GRAPH_ROW_STRIDE stays exported for it.
- Readability: row rhythm (28-32px), three ink levels for title/meta/owner,
  truncation with title hints, current-row and hover expressed as an accent bar
  plus a hover fill (no shadows), phase frames and edges back on the l1/l2
  hairlines, control cluster uniformly 28px, drawer durations on tabular
  figures, kill action revealed on hover/focus without shifting the row, no
  horizontal overflow at 360px.
- Task window: the markdown body is pulled onto the page scale (12px body,
  12/13px headings, tightened list indent and paragraph spacing) while the
  shared MarkdownText/markdownTextProps contract is untouched.
- Cleanup: dead stylesheet rules, unused TSX exports and helpers, stale
  comments that still described the retired Variant-D canvas, zero-reference
  i18n keys across the dictionaries, and the Tailwind/shadcn/Variant-D
  narrative in the design doc, AGENTS.md and the plugin guide (kept as one
  short "why it was rolled back" section).

Verified here: typecheck and lint clean; 133 files / 1413 tests; build with no
radix-ui or --tw- strings in lib/client.js (988.9 KiB); the 70-assertion
real-browser contract at 70/70 with the 20 reference screenshots regenerated;
mount e2e 7/7.

src/client/TasksGraph.tsx

@@ -1,11 +1,11 @@
 /**
- * The workflow-graph mode of the Tasks page (the approved Variant-D canvas):
- * layered agent/workflow nodes over bezier edges on a dotted grid, drag-pan
- * from the BACKGROUND only (never from a node — the mockup's rule; capturing
- * pointers on the container is what silently swallowed node clicks), wheel
- * zoom to the cursor, dashed phase frames, fold aggregate nodes, and the
- * bottom-right horizontal control cluster (view toggle / zoom out / level /
- * zoom in / fit) that stays reachable in BOTH modes.
+ * The workflow-graph mode of the Tasks page: layered agent / workflow nodes
+ * over bezier edges on a dotted grid, drag-pan from the BACKGROUND only
+ * (never from a node — capturing pointers on the container retargets the
+ * derived click and silently swallows node clicks), wheel zoom to the cursor,
+ * dashed phase frames, fold aggregate nodes, and the bottom-right horizontal
+ * control cluster (view toggle / fold / zoom out / level / zoom in / fit)
+ * that stays reachable in BOTH modes.
  *
  * Fitting: the canvas auto-fits while the reader has not touched the view,
  * re-running on container resize and layout growth (the sidebar mounts
@@ -13,8 +13,9 @@
  * on both axes and scaling UP to {@link FIT_MAX_SCALE} so a small tree fills
  * the narrow panel instead of hugging the top-left corner.
  *
- * Cards: the page sheet's node recipe with a TWO-line clamped title (the 68px
- * card reserve in tasks-graph-layout.ts is sized for that second line) and the
+ * Cards: the node card recipe of tasks-graph.module.css with a TWO-line
+ * clamped title (the card reserve in tasks-graph-layout.ts is sized for that
+ * second line, plus one row per live / task line the card renders) and the
  * full name in the `title` attribute. While the root catalog hydrates, an
  * empty canvas shows the same hint as the tree (`loading`).
  */
@@ -57,11 +58,12 @@ const FIT_MAX_SCALE = 1.15
 const CLICK_TOLERANCE_PX = 4
 
 /**
- * Card line 1 of an agent / run node: the page sheet's node title with the
+ * Card line 1 of an agent / run node: the canvas node title with the
  * truncation swapped for a TWO-line clamp — a single ellipsized line left too
- * few CJK characters to tell two siblings apart, and `GRAPH_NODE_H` in
- * tasks-graph-layout.ts reserves the card height for that second line. The
- * untruncated name stays in the `title` attribute.
+ * few CJK characters to tell two siblings apart, and `nodeHeight` in
+ * tasks-graph-layout.ts reserves the card height for that second line (plus
+ * one row per live / task line below it). The untruncated name stays in the
+ * `title` attribute.
  */
 const NODE_TITLE = canvasCss.nodeTitle
 /** The fold aggregate's title: the same clamp on the receding plain ink. */
@@ -95,7 +97,8 @@ export interface TasksGraphProps {
   loading?: boolean
 }
 
-/** The shared view-mode toggle (glyph + label, per the mockup). */
+/** The shared view-mode toggle (glyph + label) both modes render in their
+ *  bottom-right control cluster. */
 export function ViewModeToggle(props: {
   mode: 'graph' | 'tree'
   onModeChange(mode: 'graph' | 'tree'): void