Problem: :CP credentials login/logout/clear is verbose and inconsistent
with other actions that are all top-level (:CP run, :CP submit, etc.).
The clear-all subcommand is also unnecessary since re-logging in
overwrites existing credentials.
Solution: replace :CP credentials {login,logout,clear} with :CP login
[platform] and :CP logout [platform]. Remove the clear-all command and
the credentials subcommand dispatch — login/logout are now regular
actions routed through the standard action dispatcher.
## Problem
The `set` and `clear` subcommands don't clearly convey their intent —
`set`
reads like a generic setter rather than an auth action, and `clear`
overloads
single-platform and all-platform semantics in one subcommand.
## Solution
Rename `set` to `login`, split `clear` into `logout` (per-platform,
defaults
to active) and `clear` (all platforms).
New API:
- `:CP credentials login [platform]` — prompt and save credentials
- `:CP credentials logout [platform]` — remove credentials for one
platform
- `:CP credentials clear` — remove all stored credentials
Problem: :CP login was a poor API — no way to clear credentials without
raw Lua, and the single command didn't scale to multiple operations.
Solution: replace login with a :CP credentials subcommand following the
same pattern as :CP cache. :CP credentials set [platform] prompts and
saves; :CP credentials clear [platform] removes one or all platforms.
Add cache.clear_credentials(), rename login.lua to credentials.lua,
update parse/dispatch/tab-complete, and rewrite vimdoc accordingly.