feat(summer): help, examples and hints for every tool command

- build runs go build under a spinner on a terminal and ends with
  'Built bin/<name> in <time>'; make:* print 'Created <path>' per file
- make:*, plugin:add, new, parity:*, docs:build, docs:sync and every
  delegate get long help and examples; delegates note that global options
  pass through to the application binary
- make:* failures (no summer.yaml, invalid plugin ID or name, existing
  artifact, unknown plugin) explain themselves and suggest a command
- docs:build and docs:sync return bonfire.Reported after the problem list
- TestCommandsDocumented covers the tool commands too
- docs: Upgrading to 0.4, delegates and global options, make: results and
  hints, the checklist for a finished command

docs/console/utilities.md

@@ -20,7 +20,7 @@ When you port an existing backend to SummerCMS, its real responses are the contr
 | `summer parity:broadcasts` | `--flow`, `--target`, `--vars`, `--listen` (default `127.0.0.1:8424`), `--out`, `--name`, `--step`, `--ids`, `--rules`, `--api-key`, `--settle` (default `500ms`), `--pending` | Runs a flow against the reference backend with a fake Centrifugo server and records the realtime publications it sends into a golden file. |
 | `summer parity:upstream` | `--listen` (default `127.0.0.1:8425`), `--ca-dir`, `--out`, `--mode` (default `script`; or `forward`), `--script`, `--vars` | Runs a loopback HTTPS recording proxy with a locally generated CA. The reference backend sends its vendor API calls through it; each call is answered from the `--script` file (or forwarded once to the vendor in `forward` mode) and written, with credentials masked, into an upstream sidecar (`<fixture>.upstream.yaml`) when the command is interrupted. |
 
-A typical port records once against the reference backend and replays against the Go backend on every change:
+Each command's help (`summer help parity:record`) explains its place in this workflow and shows examples. A typical port records once against the reference backend and replays against the Go backend on every change:
 
 ```sh
 summer parity:record --spec testdata/parity/posts.spec.yaml --target http://127.0.0.1:8000 --output testdata/parity/posts.yaml --vars /tmp/parity/vars.yaml
@@ -45,6 +45,6 @@ summer docs:sync
 summer docs:serve
 ```
 
-`docs:build` fails, and writes nothing, when a page names an identifier that does not exist, links to a missing page or anchor, shows a command that neither `summer` nor an application binary has, or has a `src=` code block that differs from its source. It also fails on a Go code block (including `golang`) without a `src=` reference, a `src=` code block inside a callout, blockquote or list item (`src=` blocks must be top-level), and a `src=` code block in a module README. A `src=` target must be code `go test ./...` compiles and runs, that is a file in the default build, inside a `Test` function or an `Example` with an `// Output:` comment, or a function one of them calls. After you change code that a page shows, run `summer docs:sync` to refresh the copies.
+`summer help docs:build` and `summer help docs:sync` show examples. `docs:build` fails, and writes nothing, when a page names an identifier that does not exist, links to a missing page or anchor, shows a command that neither `summer` nor an application binary has, or has a `src=` code block that differs from its source. It also fails on a Go code block (including `golang`) without a `src=` reference, a `src=` code block inside a callout, blockquote or list item (`src=` blocks must be top-level), and a `src=` code block in a module README. A `src=` target must be code `go test ./...` compiles and runs, that is a file in the default build, inside a `Test` function or an `Example` with an `// Output:` comment, or a function one of them calls. After you change code that a page shows, run `summer docs:sync` to refresh the copies.
 
 `docs:serve` listens only on a loopback address unless you pass `--allow-remote`. Use it to preview search, which browsers block when you open the built files directly from disk.