Add language and product logos

[tony]

Add language-colored libtmux artwork to the project and package READMEs (1 headers). Library packages use the cog, workspace packages use the tmuxp tiles, and MCP packages use the MCP overlay.

The assets include SVG and transparent 512px PNG files. .github/social-preview.png provides the cog image for repository sharing previews. Package file lists include the artwork where applicable.

Validation

• SVG and PNG bytes match the reviewed logo kit; PNG dimensions are 512 × 512.
• README image paths resolve and executable code fences are unchanged.
• git diff --check passed.
• Sphinx dirhtml build passed; emitted OG and Twitter images and icons were checked. Six Python identity files byte-match the docs-site root. Ruff checks passed for docs/conf.py.

The Sphinx site now uses the shared Python artwork, a 1200 × 630 Open Graph card, a separate Twitter card, and a 180px Apple touch icon. Existing Python README title placement is preserved.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 52.37%. Comparing base (9fd13c3) to head (473628e).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #760   +/-   ##
=======================================
  Coverage   52.37%   52.37%           
=======================================
  Files          26       26           
  Lines        3729     3729           
  Branches      747      747           
=======================================
  Hits         1953     1953           
  Misses       1472     1472           
  Partials      304      304           

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