Document completed console migration: prompt-toolkit/Rich REPL as sole interactive console

[sodejm]

Motivation

• Consolidate interactive console documentation to reflect that the prompt-toolkit/Rich REPL is the supported and only interactive console surface after the cmd2 retirement and migration work.
• Remove references to the temporary cmd2 fallback, the --legacy-console switch, and cmd2-specific authoring patterns so docs match the current implementation.
• Clarify the transport-neutral command registration and module-authoring model so authors target ModuleDescriptor/CommandSpec and thin service dispatchers rather than terminal-specific classes.

Description

• Updated README startup guidance to identify the prompt-toolkit/Rich REPL as the only supported interactive console and adjusted the wording to reflect the consolidation. (edited README.md)
• Rewrote the console guide to remove legacy/fallback language, document strict REPL parsing and navigation controls, and add a new "Command registration" section describing ModuleDescriptor/CommandSpec driven commands. (edited docs/CONSOLE.md)
• Updated the REPL architecture doc to state consolidation is complete, remove --legacy-console compatibility paths, add a command registration model section, and clarify allowed dependencies and future work scope. (edited docs/REPL_ARCHITECTURE.md)
• Replaced cmd2-centric module authoring guidance with the descriptor/spec-based workflow and explicit guidance that modules remain thin and UI-independent. (edited docs/MODULE_AUTHORING.md)
• Extended privacy/consent and threat-model docs to reference the prompt-toolkit/Rich REPL boundary, privacy-filtered completion, no-echo secret handling, history redaction, and related controls. (edited docs/PRIVACY_AND_CONSENT.md, docs/THREAT_MODEL.md)

Testing

• Ran make lint which failed in this environment because .venv/bin/ruff is missing (environment-local tooling not present), so lint checks could not complete here.
• Verified via a targeted search that references to cmd2, --legacy-console, CommandSet, and other legacy/fallback phrases were removed or updated by running the repository search command used during the update, which returned no residual matches for those legacy terms in the edited docs.

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[chatgpt-codex-connector]

Restore the legacy-console compatibility note

In environments where operators still need the cmd2 fallback, this statement is inaccurate: src/ancestryllm/cli.py:349-352 still special-cases ancestry --legacy-console and launches AncestryConsole, and the regression test test_main_uses_default_shell_legacy_console_and_preserves_one_shot_dispatch still asserts that path works. Removing the documented compatibility path makes the console guide and migration status misleading until the reachable flag and shipped cmd2 console are actually removed.

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