kit init creates no kit.toml for applications, so kit add dead-ends
## Symptom
From a new user's first-run report (Reddit):
```
mkdir demo && cd demo
kit add gitlab.com/kit-lang/packages/kit-crooner.git
Error: No kit.toml found in current directory or parents
kit init demo # creates src/main.kit etc. but NO kit.toml
kit add ... # fails the same way
```
The user reasonably concluded an app must become a package (`kit init --package`) just to consume packages.
## Root cause
`init` only wrote kit.toml for `--package` projects, and the manifest parser required a `[package]` section (name/version only parsed there), so application manifests could not exist at all.
## Fix (applied)
- New `[application]` manifest section: same keys as `[package]` (name, version, entry-point, ...) but `is_package` stays false — not publishable, dependencies install project-locally.
- Plain `kit init` now emits an application kit.toml (`generateDefaultAppManifest`); `--package` unchanged.
- Names derived from directory basenames are sanitized to valid kebab-case (`sanitizeManifestName`, e.g. "My App_2" → "my-app-2").
- `kit add` with no manifest anywhere up the tree: prompts to create an application kit.toml on a TTY, honors `--init` non-interactively, otherwise errors with a hint pointing at `kit init`. `kit install`'s not-found error gained the same hint.
- The init pre-push hook now keys off `is_package` instead of manifest existence.
Verified end-to-end: init → add → install → run all work in a fresh application project. Unit tests added for `[application]` parsing, generation, and name sanitization. Docs note: the website guide needs a paragraph on application manifests.
issue