Extract Tableau View

Extract exact values from a Tableau view via the Connected App (JWT).

Self-describing for the context agent / Train / external callers:

• describe_only, no connection_id -> list this org's Tableau connections with {id, url, site_id, has_pat, has_jwt, sandbox_credentials} so the caller learns what's activated and which row its own TABLEAU_* env vars belong to.
• describe_only + connection_id, no view -> that connection's {has_pat, has_jwt}.
• describe_only + a view -> {worksheets, filters, parameters} for discovery.
• capture_evidence -> one same-session bundle containing controls, visual specifications, exact values, and the JWT-authenticated rendered image.
• otherwise -> {worksheets:[{name, columns, rows:[[{value, formatted_value}]]}]}.

Identify a view by view_id/view_name (resolved to a contentUrl over PAT) or pass view_content_url directly to skip resolution (cheaper, and works on JWT-only connections). Exact-value paths require Connected App (JWT) creds; without them returns 409 so the caller falls back to the PAT catalog.