This commit upgrades TypeScript to the latest version 5.3 and introduces
`verbatimModuleSyntax` in line with the official Vue guide
recommendatinos (vuejs/docs#2592).
By enforcing `import type` for type-only imports, this commit improves
code clarity and supports tooling optimization, ensuring imports are
only bundled when necessary for runtime.
Changes:
- Bump TypeScript to 5.3.3 across the project.
- Adjust import statements to utilize `import type` where applicable,
promoting cleaner and more efficient code.
This commit changes `WatchSource` signatures into `Readonly<Ref>`s.
It provides two important benefits:
1. Eliminates the possibility of `undefined` states, that's result of
using `WatchSource`s. This previously required additional null checks.
By using `Readonly<Ref>`, the state handling becomes simpler and less
susceptible to null errors.
2. Optimizes performance by using references:
- Avoids the reactive layer of `computed` references when not needed.
- The `watch` syntax, such as `watch(() => ref.value)`, can introduce
side effects. For example, it does not account for `triggerRef` in
scenarios where the value remains unchanged, preventing the watcher
from running (vuejs/core#9579).
