fix: fall back to name lookup for UUID-shaped workspace names (#24340)

`namedWorkspace` in `cli/root.go` parsed workspace identifiers with
`uuid.Parse` first and returned immediately on success, even when no
workspace had that UUID as its actual ID. This caused 404 errors for any
workspace whose name was a valid 32-char hex string (dashless UUID).

- Add `codersdk.ResolveWorkspace`: tries UUID lookup first, falls back
to name lookup on 404. `NameValid` guard skips the fallback for standard
dashed UUIDs (36 chars > 32-char name limit).
- Export `codersdk.SplitWorkspaceIdentifier`, replacing the duplicate
`splitNamedWorkspace` in `cli/root.go` (uses `strings.Cut`).
- Delete `namedWorkspace` from `cli/root.go`; all 28 call sites now use
`client.ResolveWorkspace` directly.
- Delete `namedWorkspace` and `splitNameAndOwner` from
`codersdk/toolsdk/bash.go`; inline `client.ResolveWorkspace`.
- Simplify `GetWorkspace` tool handler to a single `ResolveWorkspace`
call.
- Unit tests via httptest mock cover UUID, name, owner/name, UUID-like
fallback, not-found, server error, transport error, and invalid
identifier paths.
- Integration tests in `cli/show_test.go` and `codersdk/toolsdk` for
workspaces with UUID-like names.

> Generated with Coder Agents

cli/create.go

@@ -68,7 +68,7 @@ func (r *RootCmd) Create(opts CreateOptions) *serpent.Command {
 
 			workspaceOwner := codersdk.Me
 			if len(inv.Args) >= 1 {
-				workspaceOwner, workspaceName, err = splitNamedWorkspace(inv.Args[0])
+				workspaceOwner, workspaceName, err = codersdk.SplitWorkspaceIdentifier(inv.Args[0])
 				if err != nil {
 					return err
 				}
@@ -104,7 +104,7 @@ func (r *RootCmd) Create(opts CreateOptions) *serpent.Command {
 
 			var sourceWorkspace codersdk.Workspace
 			if copyParametersFrom != "" {
-				sourceWorkspaceOwner, sourceWorkspaceName, err := splitNamedWorkspace(copyParametersFrom)
+				sourceWorkspaceOwner, sourceWorkspaceName, err := codersdk.SplitWorkspaceIdentifier(copyParametersFrom)
 				if err != nil {
 					return err
 				}