Local memory-plane setup: native/Docker/endpoint recommendations, honest degradation

[TheGreatAxios]

Summary

• bun run setup:memory (scripts/setup-memory.ts) probes this machine and recommends how to turn on the memory plane's embedding and reranking, in the platform's preferred order: native Ollama first, Docker for the pieces with no good native story (the TEI reranker, Gotenberg), a remote endpoint always available as a third option.
• mountMemory now fails loudly at boot when only one of RERANK_BASE_URL/RERANK_MODEL is set, instead of a half-configured reranker surfacing as a confusing runtime failure later — matches the existing OAuth-pair pattern in apps/hub/src/config.ts.
• .env.example, README.md, and docs/local-dev.md spell out what degrades and how visibly: no embedding configured means memory tools answer "not set up" and search finds nothing, and setting EMBED_BASE_URL later does not retroactively embed rows written before — no automatic backfill. No reranker means search still works, just less well-ordered.
• Added GOTENBERG_URL to .env.example, matching the same native/Docker/endpoint story (Docker or remote endpoint; no native path).

What this deliberately does NOT change

• The memory plane already shares DATABASE_URL with the rest of the hub (its own memory Postgres schema) — no separate KNOWLEDGE_DATABASE_URL was introduced; that would have contradicted the existing convention in apps/hub/src/memory-mount.ts.
• No second setup path: this extends the existing @corbits/memory mount and .env.example rather than inventing a parallel one.

Test plan

• bun test apps/hub/src/memory-mount.test.ts — 5 pass, 2 DB-gated skipped
• bun test scripts/setup-memory.test.ts — 6 pass
• bun run scripts/setup-memory.ts run manually against this machine (native Ollama found, Docker unreachable) — printed the expected native-embedding + endpoint-reranker recommendation and exited promptly