feat(onboarding): folder name follows the project name, and project ids are UUIDs (#89)

The paste prompt now carries the project's name so an agent recommends a
folder of that name; with no project at all the recommendation is `shared/`
(and `bdrive init shared` names the new project after the folder), replacing
the old `wiki/` default.

New project ids are UUIDs instead of `p-` + 8 hex chars. The route validator
still accepts the legacy shape — ids are permanent — and the client-side URL
parsers (remote/http.go, bdrive share) now only check the shape of a URL
segment, leaving the hub as the single authority on which ids are valid.

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/aws/aws-sdk-go-v2/config v1.32.25
 	github.com/aws/aws-sdk-go-v2/service/s3 v1.103.3
 	github.com/aws/smithy-go v1.27.2
+	github.com/google/uuid v1.6.0
 	github.com/jackc/pgx/v5 v5.10.0
 	github.com/mattn/go-isatty v0.0.20
 	github.com/spf13/cobra v1.10.2
@@ -56,7 +57,6 @@ require (
 	github.com/go-logr/logr v1.4.3 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/google/s2a-go v0.1.9 // indirect
-	github.com/google/uuid v1.6.0 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.16 // indirect
 	github.com/googleapis/gax-go/v2 v2.22.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect