dogfood: @webjsdev/core subpath exports lack a types condition (no types for /directives, /task, etc.)

[vivek7405]

Problem

Importing from @webjsdev/core SUBPATHS has no type information, so import { watch } from '@webjsdev/core/directives' or import { Task } from '@webjsdev/core/task' red-squiggles (no types found) under nodenext/bundler module resolution. Surfaced alongside #388 while dogfooding the VSCode extension (#382), but is a DISTINCT root cause from the index.d.ts drift.

Root cause

In packages/core/package.json, several subpath entries in the exports map have NO types condition and resolve only to a built .js bundle with no sibling .d.ts:

Subpath	Resolves to	Sibling .d.ts?
./directives	./dist/webjs-core-browser.js	none (src/directives.d.ts missing)
./context	./dist/webjs-core-browser.js	none
./task	./dist/webjs-core-browser.js	none
./client-router	./dist/webjs-core-browser.js	none
./lazy-loader	./dist/webjs-core-lazy-loader.js	none
./testing	./dist/webjs-core-testing.js	none

AGENTS.md tells agents to import from these subpaths (e.g. watch from @webjsdev/core/directives, Task / TaskStatus from @webjsdev/core/task, context from @webjsdev/core/context), so this is on the documented happy path.

Fix

• Add a types condition to each subpath exports entry pointing at a real .d.ts (authored src/<name>.d.ts, mirroring how ./component already points at src/component.d.ts).
• Author the missing src/{directives,context,task,client-router,lazy-loader,testing}.d.ts declarations.
• Extend the dogfood: package .d.ts files drift from runtime exports (many import type errors) #388 guard idea: a test that every exports subpath with a JS target also has a resolvable types target (counterfactual: removing one fails it).

Acceptance criteria

• import { watch } from '@webjsdev/core/directives', import { Task, TaskStatus } from '@webjsdev/core/task', and the other documented subpath imports type-check clean.
• Every JS-bearing exports subpath has a types condition resolving to a real .d.ts.
• A test enforces the subpath types invariant (counterfactual proven).
• Docs unaffected (the subpaths were always documented).

Related: #388 (the index.d.ts named-export drift).