feat(validator): add bare FastAgent + Pallas validator for Mnemosyne MCP

A self-contained sub-project under validator/ that wraps Mnemosyne's MCP
server in a single FastAgent. Use it to confirm — outside of Daedalus —
that Mnemosyne's MCP transport works, every tool registers, args/responses
round-trip, and an LLM can actually drive the tools.

The validator is its own Pallas-consuming project with its own pyproject
(pallas-mcp + fast-agent-mcp), agents.yaml, and fastagent.config.yaml —
matching the pattern used by Iolaus and other Pallas consumers. It does
not import Mnemosyne Python code; it only speaks MCP over HTTP.

The agent never sets workspace_id, so all calls run against the global
scope (libraries with workspace_id IS NULL). Workspace-scoped validation
will come once Daedalus's chat path is wired (Daedalus injects
workspace_id server-side, force-overwriting whatever the LLM produces).

Default model is openai.Qwen3.5-35B-A3B-UD-Q4_K_XL.gguf served by
llama.cpp at nyx.helu.ca:22079/v1. Token provisioning via
`python manage.py create_mcp_token --user <u> --name validator`.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

validator/.env.example

@@ -0,0 +1,9 @@
+# Mnemosyne Validator — environment variables
+#
+# Copy to .env and adjust as needed. Loaded by Pallas at startup
+# (without overwriting already-set vars).
+#
+# OPENAI_BASE_URL is also set in fastagent.config.yaml; this is here for
+# parity with the standard Pallas-consumer layout.
+
+OPENAI_BASE_URL=http://nyx.helu.ca:22079/v1