fix(tools): expose remember to local-model agents

[alpibrupa]

Summary

• `minimal_tools()` — the curated toolset every local-model (litellm/ollama/vllm) agent variant is built from via `dynamic_tools()` — never included `remember_tool`, even though `build_permission()` allows it unconditionally and it's a single cheap `[net, io, proc]` tool (append one JSONL line).
• `refactor_dynamic_tools()` had the identical gap against its own declared `refactor_permission()`, which explicitly lists `"remember"` in its allowlist.
• Net effect: a local-model build or refactor agent could never call `remember`, silently defeating the memory system's propose step for the provider path most of this project's local dogfooding actually uses.

Fixes #110

Test plan

• `lex check src/tools/index.lex` — ok
• `lex fmt --check` — formatted
• Full repo sweep (`lex check` over every tracked `.lex` file) — all pass
• `lex test` — 4/4 passed
• `lex doc-sync --check` — current
• Confirmed via live ACP session before this fix: a local model (qwen3.8:27b-mlx via litellm) instructed to call `remember` correctly reported it had no such tool, listing exactly `minimal_tools() + load_toolset`'s names — proving the gap rather than a model-reliability issue