fix(sdk): document exact versioned VCT values

[shibutatsu]

Description

Aligns the four mandate VCT descriptions with their exact versioned const and default values. The generated Pydantic metadata and SDK README now use the same values, and a regression test covers all four mandate types.

The dictionary additions and Markdown annotations only clear pre-existing incremental lint findings in the files this patch touches.

• Follow the CONTRIBUTING guide
• Use a Conventional Commit title
• Update the relevant SDK docs
• Full repository checks pass (the two pre-existing intermediate-hop tests still fail on unchanged main; the repository-wide Biome CI issue is tracked in Lint Code Base: super-linter ignores flat eslint.config.js; BIOME_LINT scans beyond PR diff #306 and a pending workflow fix is in fix(samples): consume accepted Payment Mandates atomically #347)

Validation:

• VCT regression tests: 4 passed
• Remaining Python suite: 190 passed, 2 known failures deselected
• Ruff, CSpell, Markdownlint, JSON parsing, and git diff --check: passed

AI assistance: Codex was used to prepare and validate this patch.

Fixes #322 🦕

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