feat: Spring Boot config files in repos

application*.properties/.yml and bootstrap* files tracked by git are
listed under Repos, with their secret-looking keys as secrets.

- Keys whose name ends like a secret (password, secret, token, key, …)
  or whose value looks like one (Jasypt ENC(...), a URL or connection
  string with a password) are listed; providers.repos.spring.keys and
  .values replace the patterns, also in a repo's .lazysecrets.yaml.
- A file's details count the keys left out; ${VAR} values are marked
  as references, and a tracked file is only marked red when a listed
  value is in plain text.
- Later YAML/properties documents name their keys after the profile:
  spring.datasource.password (prod).
- Maven's @placeholders@ parse; Argo CD's applications.yaml and Helm
  templates aren't Spring files.
- A green leaf icon, themeable with springColor.

docs/keys.md

@@ -53,7 +53,7 @@ match case exactly.
 | `Y` | copy the reference (`@Microsoft.KeyVault(...)`, key/certificate URL, `{{secrets/scope/key}}`) |
 | `v` | versions of the selected item (Azure); `space`/`y`/`Y` then act on that version; `esc`, `⌫` or `v` to go back |
 | `o` | open the selected item in the browser (over SSH: copy the link) |
-| `e` | open the selected SOPS or `.env` file, or a secret's file at its line ([how](repos.md#opening-files)) |
+| `e` | open the selected SOPS, `.env` or Spring file, or a secret's file at its line ([how](repos.md#opening-files)) |
 | `s` / `S` | copy a [link](sharing.md) to the selected item / share menu (also env files, [encrypted](sharing.md#sharing-env-files)) |
 | `ctrl+o` | open a link or reference (or just paste one) |
 | `x` | [custom commands](custom-commands.md) |