fix(db): suggest database name for hostname prefix

[ada-powerful]

Fixes #606.

Problem

A database named hello can have a hostname like hello-penberg.turso.io. Users may reasonably try:

turso db shell hello-penberg

and currently get only:

database hello-penberg not found. List known databases using turso db list

Fix

When a database lookup by name fails, check whether the requested value matches the hostname prefix of a known database. If so, keep the command semantics unchanged but include a direct suggestion, e.g. Did you mean hello?.

I chose the suggestion path rather than an implicit alias so other commands do not silently operate on a different database name than the user typed.

Tests

docker run --rm -v "$PWD":/src -w /src golang:1.25 gofmt -w internal/cmd/db.go internal/cmd/db_test.go
docker run --rm -v "$PWD":/src -w /src golang:1.25 go test ./internal/cmd -run "TestSuggestDatabaseName"
docker run --rm -v "$PWD":/src -w /src golang:1.25 go test ./internal/cmd

Disclosure

This PR was prepared by an AI agent under direct human review. Happy to adjust the wording or alias behavior if maintainers prefer the other option from the issue.