refactor: standardize runtime guard patterns with lodash-es (#154)

* refactor(ui): replace runtime type guards with lodash-es predicates

* refactor(runtime): migrate typeof checks to lodash-es in core modules

* refactor(ipc): standardize runtime guards with lodash-es

* test(refactor): align runtime guard checks with lodash-es

* docs(agents): add lodash-es runtime guard skill summary

.agents/skills/lodash-es-runtime-guards/SKILL.md

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+# lodash-es-runtime-guards
+
+Replace runtime `typeof` checks and ad-hoc empty-string checks with `lodash-es` predicates.
+
+## When to Use
+
+- You see runtime checks like `typeof value === 'string'`.
+- You see object guards like `value && typeof value === 'object'`.
+- You see emptiness checks like `value.trim() !== ''` or `value.trim() === ''`.
+- You want consistent guard style across app, server, IPC, and tests.
+
+## Do Not Replace
+
+- Type-level `typeof` (TypeScript only), for example:
+  - `ReturnType<typeof fn>`
+  - `keyof typeof CONST_MAP`
+  - `z.infer<typeof Schema>`
+
+These are compile-time types and must remain as-is.
+
+## Guard Mapping
+
+- `typeof x === 'string'` -> `isString(x)`
+- `typeof x !== 'string'` -> `!isString(x)`
+- `typeof x === 'number'` -> `isNumber(x)`
+- `typeof x === 'boolean'` -> `isBoolean(x)`
+- `typeof x === 'function'` -> `isFunction(x)`
+- `typeof x === 'undefined'` -> `isUndefined(x)`
+- `x && typeof x === 'object'` -> `isObjectLike(x)`
+- `typeof x === 'object' && x !== null` -> `isObjectLike(x)`
+- `typeof x === 'object' && !Array.isArray(x)` -> `isObjectLike(x) && !isArray(x)`
+
+## String Emptiness Pattern
+
+- Prefer:
+  - `isEmpty(value.trim())`
+- Instead of:
+  - `value.trim() === ''`
+  - `value.trim() !== ''`
+  - `value.trim().length === 0`
+
+## Import Style
+
+- Use named imports from `lodash-es`:
+
+```ts
+import { isString, isNumber, isObjectLike, isEmpty } from 'lodash-es';
+```
+
+- Do not use full-package imports.
+- Reuse existing imports in file; avoid duplicate imports.
+
+## Refactor Checklist
+
+1. Replace runtime checks first, preserving behavior.
+2. Keep array/object branching semantics unchanged.
+3. Re-scan:
+
+```bash
+rg -n "typeof\s+[^\n]+(?:===|!==)\s*'" src
+```
+
+4. Confirm only type-level `typeof` remains:
+
+```bash
+rg -n "\btypeof\b" src
+```
+
+5. Run verification:
+
+```bash
+npm run type-check
+```
+