chore: add coding conventions from nerve

- CLAUDE.md: functional-first, type over interface, no optional props, Result type
- biome.json: lint + format config (Biome 1.9)
- tsconfig.json: strict mode, composite project references
- .cursor/rules: global conventions + no-dynamic-import

Adapted from uncaged/nerve for bun workspace.

小橘 <xiaoju@shazhou.work>

.cursor/rules/no-dynamic-import.mdc

@@ -0,0 +1,27 @@
+---
+description: Ban dynamic import() in production code — use static imports instead
+globs: packages/*/src/**/*.ts
+alwaysApply: true
+---
+
+# No Dynamic Import in Production Code
+
+## Rule
+
+Do NOT use `await import()` or dynamic `import()` expressions in production source code.
+Always use static top-level `import` statements.
+
+## Exception (must include a comment explaining why)
+
+1. **Bundle loader** — loads user-authored workflow bundles whose paths are only known at runtime
+
+When suppressing, add a comment directly above:
+
+```ts
+// Dynamic import required: user bundle path resolved at runtime
+const mod = await import(bundlePath);
+```
+
+## Test Files
+
+Test files (`__tests__/**`) are exempt.