Add /impeccable generate: agent-initiated live variants (Node-era squash)

Squash of the ten commits reviewed on PR #626, plus the last review
round's connection-aware roll call, before the rebase onto the Rust
engine: the generate command reference and router row, the overlay's
agent-target handling (roll call, leases, replay, rescue), the Node-era
live-server routes and live-generate CLI, the hook stand-down, the pricing
cards e2e fixture, and the unit, contract, e2e, and skill-behavior tests.
The server, CLI, hook, and pin halves are ported to the engine crates in
the commits that follow.

AI-assisted: implemented and tested with Claude Code under maintainer
direction.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

skill/scripts/command-metadata.json

@@ -19,6 +19,10 @@
     "description": "Interactive live variant mode. Select elements in the browser, pick a design action, and get AI-generated HTML+CSS variants hot-swapped via HMR. Requires a running dev server. Use when you want to visually experiment with design alternatives in real time.",
     "argumentHint": ""
   },
+  "generate": {
+    "description": "Agent-driven live variant generation. Boots live mode, finds the named element on the open page, scrolls the browser to it, and delivers N variants in the requested direction for the user to cycle and accept. Use for requests that name an element and a direction, like 'generate 3 bold variants of the pricing cards', skipping manual element picking.",
+    "argumentHint": "[count] [direction] variants of [element]"
+  },
   "adapt": {
     "description": "Adapt designs to work across different screen sizes, devices, contexts, or platforms. Implements breakpoints, fluid layouts, and touch targets. Use when the user mentions responsive design, mobile layouts, breakpoints, viewport adaptation, or cross-device compatibility.",
     "argumentHint": "[target] [context (mobile, tablet, print...)]"