feat(lib): add man_lib, pydantic model to parameter-doc introspection

[speriaswamy-amd]

Part 9 of 14 in a stack for AIMVT-276.
Base: #341.

Why

Config parameter docs currently live only in scattered _comment_*/
_example_* JSON keys and prose READMEs, both of which drift from the
pydantic schemas that actually validate the config. man_lib introspects a
pydantic model directly so documentation is generated from the single source
of truth instead of hand-maintained in parallel.

What changed

• Added cvs/lib/man_lib.py: walks a pydantic model's fields recursively
  (including nested models, lists of models, and dict-of-model containers),
  and renders the result as human-readable text or JSON. Supports querying a
  specific parameter or section by name.
• Added cvs/lib/unittests/test_man_lib.py covering discovery, nesting,
  required/default/constraint reporting, alias handling, and both render
  formats — built against local toy models, independent of the real schemas.