codegen: consume the IR-derived cli.json from genkit

Switch the CLI to genkit's native cli_v1 producer (`genkit update-sdk`,
mode cli_v1). The cli.json schema keys/refs now use the Go SDK's
package.PascalName rendering and the file carries every message —
including request/response wrappers, which are inert for the CLI since it
reads only the schemas its commands reference.

- derive DoNotSuggest from launch_stage == PRIVATE_PREVIEW instead of the
  dropped preview flag (cli_json.go, parser.go), sourcing the signal from
  the single launch-stage source of truth
- Taskfile generate-cli-json: build genkit from universe HEAD and run
  update-sdk, since the cli_v1 producer is decoupled from the spec
- regenerate annotations, jsonschema (+ for-docs), and docs; compute.Kind's
  description now resolves via the package.PascalName key
- cli_json_test: assert the spec sha via the _openapi_sha file (genkit no
  longer writes it into cli.json metadata)

Co-authored-by: Isaac

Author: pietern

.codegen.json

@@ -1,5 +1,5 @@
 {
-    "mode": "cli_v0",
+    "mode": "cli_v1",
     "api_changelog": true,
     "formatter": "go run golang.org/x/tools/cmd/goimports@latest -w $FILENAMES && go fmt ./...",
     "version": {