refactor: remove deja-vu #321

Why

deja-vu indexes every agent history into a user-level index, so it cannot fit a project-only kit (design Decision 4). One card: the code, flags and tests are interlocked across 17 files and must leave together.

In scope

Delete the three deja-vu modules (1,430 lines) and their references in 17 files; remove five flags; delete 26 test files; delete the companion registry (G5); tag retired mcp__deja-vu__* rows in the tool-family map.

Out of scope

Docs and ADR-0035 (#322).

Acceptance criteria

• No source file names deja-vu outside the tool-family retired tag
• The five flags fail as unknown
• pnpm test passes

Dependencies

Blocked by: #320

Blocks: #322, #330, #385

Plan

• Release: 4.0.0-beta.1
• Size: size:L · Workstream: ws:project-scope
• Epic: feat: project-scope P0, removals and the enforcement baseline (epic) #295
• Card: P0-01 in the card inventory
• Sources: Design (docs(plans): project-scoped management design and its prerequisites #289) Removing deja-vu; Supersession ledger (docs(plans): v4 GA master plan, supersession ledger and v5 registers #290) G5

Verification

• pnpm test
• rg -i deja src bin