docs(readme): stop the logo filling the page and thin the badge wall - #4222

The logo is an SVG with no intrinsic width, so GitHub rendered it at the
full width of the README column -- 734x246 on a desktop viewport, a wall
of logo before a single word of text. It also used the
#gh-light-mode-only / #gh-dark-mode-only fragment hack, which GitHub has
since superseded with <picture> and prefers-color-scheme.

Replaced with a <picture> element at a fixed 340px, which both bounds the
logo and drops the hack.

The badge block had eight entries of ragged widths. Two carried no
information: 'Open Source' says what the Apache-2.0 badge beside it
already says, and a hand-set 'Status: Active' is a claim rather than a
measurement -- the commit-activity badge next to it is the real thing,
and the static one was also served over plain http. Both removed.

The remaining six are ordered identity, then health, then support, and
the licence badge now points at the LICENSE file rather than at
opensource.org.

Co-Authored-By: Claude <[email protected]>
Signed-off-by: tym83 <[email protected]>

Reverted the <picture> element. #gh-light-mode-only keys off GitHub's
account theme; prefers-color-scheme keys off the OS. They diverge for
anyone who pins a GitHub theme rather than syncing with the system, and
the combination 'OS dark, GitHub light' renders the white logo on white.
The fragment form is correct in all four combinations. Kept the width
attribute, which was the actual fix -- the logo stretched to 734px
because the SVG has no intrinsic width, not because of the fragment.

Also from review:
- /docs/roadmap/ on the website is a 404; linked ROADMAP.md instead.
- Added a project-documents table. The README linked one of the eight
  policy files in the repository root; governance, code of conduct,
  security policy and adopters are what a newcomer and a CNCF reviewer
  both look for first.
- Added both Slack channels. The community section listed Telegram only,
  while the CNCF-hosted #cozystack channel went unmentioned.
- Added the CLOMonitor badge, the standard CNCF project-health signal.
  It currently reports A.
- semver.org was the one remaining plain-http link, which sat oddly next
  to dropping a badge for the same reason.
- The commit-activity badge linked to the contributors graph.
- 'free platform' reads as price now that the Open Source badge is gone.
- 'CNCF Sandbox Level Project' is legacy phrasing.
- Fixed an ungrammatical sentence in Contributions.

Co-Authored-By: Claude <[email protected]>
Signed-off-by: tym83 <[email protected]>

Final review nits: the project-documents table had an empty header row
that GitHub renders as a blank band, ROADMAP ended up linked twice once
the table landed, and one sentence in Contributions still read wrong.

Co-Authored-By: Claude <[email protected]>
Signed-off-by: tym83 <[email protected]>