feat(api): generate --data/--data-file flags and body schema help (#156)

Reimplements PR #156 against the typed-client generator landed in #160
(6fd1f02). The original PR was authored against the pre-#160 generator,
whose entire schema parser, client signatures, and emit functions were
replaced — making a literal rebase impossible.

What

For every body-bearing endpoint the generator now emits two flags:

  --data <json>       Request body as a raw JSON string
  --data-file <path>  Read request body JSON from a file (- for stdin)

Body resolution precedence in the generated `RunE`:
  --data wins; else --data-file (file, or os.Stdin for `-`); else fall
  back to piped stdin so existing usage keeps working.

Each branch JSON-decodes directly into the typed `api.XInput` struct
(the post-#160 shape), so path/query overrides still win because they
populate `in` after.

The body schema is surfaced in the cobra `Long` help: sorted top-level
property names with JSON-style type hints, marking required fields,
looked up from `r.schemas[ep.BodySchema]`. Unknown / property-less
schemas fall back to a generic `Request body: raw JSON` note.

Regenerated `internal/commands/*` via `go run ./scripts/generate`. The
diff is large because every body-bearing command changed — expected.
`internal/api/*` is unchanged.

Verification

  GOWORK=off CGO_ENABLED=0 go build ./...   # OK
  GOWORK=off go vet ./...                   # OK
  GOWORK=off go test ./...                  # OK
  go run ./cmd/cli api manager create-threat-investigations --help
    → Long now lists every field, --data / --data-file flags appear.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: tim-thacker-nullify