docs: reach 100% YARD coverage and add doc rake tasks

[tas50]

What

Measured with --private, kitchen-cloudstack was at 65% — 22 of 44 methods, four constants, and the Kitchen::Driver namespace undocumented — with no way to generate or measure docs.

• Everything remaining documented → 100%.
• .yardopts added as the single source of truth.
• rake doc and rake doc_coverage added; yard in a :docs bundle group.

Two things worth calling out

create, destroy, and status had # (see Base#create) directives. YARD doesn't count those as documentation, and more importantly they told a reader nothing about what this driver does differently — destroy tears down the public address, port forward, and firewall rule before the instance and then scrubs credentials from the state file; status maps CloudStack's own state names onto Test Kitchen's live/not-live. They now have real docstrings, and the stranded directives are removed rather than left sitting above the new prose.

The four undocumented constants shared one comment. JOB_SUCCEEDED, JOB_FAILED, DEFAULT_POLL_INTERVAL, and DEFAULT_TIMEOUT sat beneath a comment that YARD attached only to JOB_RUNNING:

# Values CloudStack reports in an async job's "jobstatus" field.
JOB_RUNNING = 0
JOB_SUCCEEDED = 1   # <- undocumented as far as YARD is concerned
JOB_FAILED = 2      # <- likewise

Each now carries its own, and the two DEFAULT_* constants name the config option that overrides them.

Verification

$ yard stats --private --protected
Modules:         2 (    0 undocumented)
Classes:         5 (    0 undocumented)
Constants:      15 (    0 undocumented)
Attributes:     11 (    0 undocumented)
Methods:        44 (    0 undocumented)
 100.00% documented

$ bundle exec rspec
63 examples, 0 failures

$ bundle exec cookstyle --chefstyle lib
6 files inspected, no offenses detected

Comments only — no behaviour change.

🤖 Generated with Claude Code