Audit and clean Wiii codebase harness after full-surface WIP

[meiiie]

Problem

A large local WIP touched backend runtime, frontend UX, LMS, voice, visual artifacts, deploy files, tests, and docs at once. That state is not safe to push directly to main or review as one PR.

Objective

Preserve the WIP safely, return the local worktree to a clean reviewable state, and add durable codebase-harness documentation inspired by large-codebase agent practices.

Scope

• Record the recovery state and stash name.
• Add a concise Wiii codebase map.
• Add backend and frontend path-specific agent guidance.
• Add an agentic large-codebase harness runbook.
• Keep runtime behavior unchanged.

Non-goals

• No production deploy.
• No runtime refactor.
• No merge of the preserved WIP.
• No deletion of unreviewed WIP.

Acceptance criteria

• main remains synced and clean.
• The large local WIP is preserved in a named stash.
• The cleanup branch contains docs and ignore-rule updates only.
• git diff --check passes.
• Diff contains no provider secrets.

Risk and rollback

Risk is low because this is documentation and harness configuration only. Rollback is reverting the docs and .gitignore exceptions.