docs: align public guidance with current APIs (#82)

## Summary

Align the public documentation and package examples with the current
DomainKit 0.7 and CapsuleDB 0.1 APIs.

## Usage

```ts
const requirement = DnsRecord.Txt.make({
  metadata,
  name: DomainName.parse("_verify.example.com"),
  policy: "append",
  ttl: 300,
  value: "verification-value",
});
```

## Lifecycle

```text
host identity and policy
  -> provider authorization
  -> organization connection
  -> exact domain attachment
  -> plan, approval, apply, and verification
```

## Changes

- Refresh release metadata, README surfaces, and the workspace lockfile.
- Replace public handwritten `_tag` examples with constructor helpers.
- Document the current connection/attachment lifecycle and
Cloudflare/Vercel restore flow.
- Expand the server reference with `Server.make`, `Server.layer`,
`createDomainKit`, and framework mounts.
- Clarify host-owned persistence and the Effect-only CapsuleDB boundary.

## Validation

- `bun run docs:audit`
- `bun run docs:build`
- `bun run --filter @domainkit/docs registry:check`
- `bun run --filter domainkit typecheck:examples`
- `bun run typecheck`
- `bun run format:check`
- `git diff --check`

## Known limitations

- The repository-wide docs typecheck still reports 49 pre-existing
Astro/Bun typing errors.
- Existing docs checks do not compile every arbitrary MDX code fence;
package examples are typechecked.