feat(translate-mcp): scaffold per-tenant translation MCP (CF-3122)

Node.js MCP server exposing translate/search_tm/upsert_glossary/record_correction
over StreamableHTTP on :9222. Routes translation calls to gemini-2.5-flash via
LiteLLM, augmented with per-tenant TM + glossary + tone profile from the
SmartTranslate pgvector DB.

Schema migration in sql/001_schema.sql already applied to smarttranslate DB.
Fleet registration in Infrastructure/litellm/config.yaml.

Refs: CF-3122 CF-3123 CF-3124 CF-3125

README.md

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+# translate-mcp
+
+Per-tenant translation MCP. Routes translations to `gemini-2.5-flash` via LiteLLM,
+augmented with per-tenant translation memory, glossary, and tone profile stored in
+the shared SmartTranslate Postgres (pgvector).
+
+- Epic: **CF-3122**
+- Scaffold: CF-3123 (this repo)
+- Schema migration: CF-3124 (see `sql/001_schema.sql`)
+- Gateway registration: CF-3125
+- Claude routing (CLAUDE.md + PreToolUse hook): CF-3126
+- Tenant profile seeding from memory: CF-3127
+
+## Tools
+
+| Tool | Purpose |
+|---|---|
+| `translate(text, tenant, target_lang, source_lang?)` | Main translation call; uses TM + glossary + tone. |
+| `search_tm(query, tenant, target_lang, ...)` | Vector TM lookup. |
+| `upsert_glossary(...)` | Manage per-tenant glossary. |
+| `record_correction(tm_id, corrected_target, tenant)` | Human-in-the-loop correction. |
+| `list_tenants()` / `get_tenant_profile(tenant)` | Inspect profiles. |
+
+## Environment
+
+```
+TRANSLATE_DB_DSN=postgresql://translate_mcp_rw:***@postgres.agiliton.internal:5432/smarttranslate
+LITELLM_URL=http://llm:4000
+LITELLM_API_KEY=sk-litellm-master-key
+TRANSLATE_MODEL=gemini-2.5-flash          # override for cost tests
+TRANSLATE_EMBED_MODEL=mxbai-embed-large
+SENTRY_DSN=...                             # optional
+```
+
+## Run locally (dev)
+
+```
+uv pip install -e .
+export TRANSLATE_DB_DSN=postgresql://...
+python -m src.server
+```
+
+## Deploy
+
+Via LiteLLM MCP gateway: add block in `Infrastructure/litellm/config.yaml`
+(see CF-3125) and `agiliton-deploy litellm`.