docs: add Cursor Cloud specific development instructions to AGENTS.md

[andykais-claude]

Summary

Sets up the Cursor Cloud development environment and documents key findings about a Deno canary regression that breaks web package builds.

Changes

• Added ## Cursor Cloud specific instructions section to AGENTS.md with:
  • Detailed documentation of the Deno canary bare specifier regression
  • Environment requirements (Deno stable, FFmpeg)
  • Key commands table (lint, test, build, dev)
  • Known test quirks

Investigation: Deno Canary Bare Specifier Regression

Root cause identified: When vite evaluates vite.config.ts, @sveltejs/kit's import_peer('svelte/compiler') loads node_modules/svelte/src/compiler/index.js. That file's import { walk } from 'zimmerframe' is resolved as a relative path (./zimmerframe) instead of using Node module resolution on Deno canary (2.7.14+d6212d4, TypeScript 6.0.3).

What was tested:

• nodeModulesDir: "manual" + npm install → Same failure (issue is in Deno's module loader, not node_modules layout)
• nodeModulesDir: "auto" + npm install overlay → Same failure
• nodeModulesDir: "none" → Different failure (lifecycle scripts can't run)
• Vite --configLoader native / --configLoader runner → Same failure
• Direct deno eval / deno run of the same import chain → Works fine

Conclusion: The issue is a Deno canary regression in how bare specifiers are resolved during vite's module evaluation. Neither changing nodeModulesDir nor using npm alongside deno install fixes it. Deno stable 2.7.14 works correctly.

Environment Verification

Service	Command	Result
Lint (core)	deno task --cwd packages/core lint	✅ 71 files
Test (core)	deno task --cwd packages/core test	✅ 26 passed, 4 known failures
Build (web)	deno task --cwd packages/web build:local	✅ Built in ~7s
Dev (web)	deno task --cwd packages/web dev	✅ Vite 7.1.8 on :5173
Test (CLI)	deno task --cwd packages/cli test	✅ 2 passed

Build output log:
web_build_local_output.log

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