feat(selfhost): tune Ollama concurrency for a shared embed+vision GPU (#4327)

[JSONbored]

Summary

• Ollama had no concurrency/residency configuration — everything was Ollama's own defaults, and OLLAMA_MEM_LIMIT (container RAM ceiling, not VRAM) was still sized for a single embedding model only (8g).
• Adds OLLAMA_NUM_PARALLEL/OLLAMA_MAX_LOADED_MODELS/OLLAMA_KEEP_ALIVE, mirroring the existing OLLAMA_MEM_LIMIT env-override pattern, and raises the memory ceiling to 20g — sized for an embed model + one vision model resident and concurrently in use on a single 24GB-class GPU without either starving the other under a busy review queue.
• See the comment on the ollama service in docker-compose.yml for the full VRAM/KV-cache reasoning (worst-case ~14-15GB of 24GB at these defaults).

Closes #4327 -- all 5 deliverables satisfied: GPU passthrough confirmed (nvidia-smi + docker inspect device reservation), before/after latency numbers posted to the issue, a batch-size recommendation shipped (#4350), and this PR promotes the previously-local-only compose changes into the tracked repo now that cutover has happened. Companion to #4350, both stemming from the GPU-migration epic #4325.

Scope

• The PR title follows type(scope): short summary Conventional Commit format.
• This PR is focused and does not mix unrelated backend, UI, MCP, docs, dependency, and deploy changes.
• This follows CONTRIBUTING.md and does not reintroduce GitHub Pages, VitePress, site/, or CNAME.
• Closes GPU passthrough for Ollama + embedding benchmark vs. the current CPU-bound setup #4327.

Validation

• git diff --check
• npm run actionlint (via npm run test:ci)
• npm run typecheck (via npm run test:ci)
• npm run test:coverage locally — new structural assertions added to test/unit/selfhost-compose-resource-limits.test.ts
• npm run test:workers (via npm run test:ci)
• npm run build:mcp / npm run test:mcp-pack (via npm run test:ci)
• npm run ui:openapi:check / npm run ui:lint / npm run ui:typecheck / npm run ui:build (via npm run test:ci) — no UI/API surface touched
• npm audit --audit-level=moderate — 0 vulnerabilities
• New behavior has structural tests: docker-compose.yml's ollama environment: block and .env.example documentation are both asserted directly (mirroring this file's existing memory-limit test pattern)

Ran npm run test:ci (full unsharded suite) end-to-end — green.

Safety

• No secrets, wallet details, hotkeys, coldkeys, user PATs, private keys, raw trust scores, private rankings, or private maintainer evidence are exposed.
• Public GitHub text stays sanitized, low-noise, and does not imply compensation guarantees or optimization tactics.
• Auth/cookie/CORS/GitHub App/Cloudflare/session changes include negative-path tests. — N/A, no such surface touched.
• API/OpenAPI/MCP behavior is updated and tested where needed. — N/A, no API/OpenAPI/MCP surface touched.
• UI changes use live API data or real empty/error/loading states. — N/A, infra-config-only change.
• Visible UI changes include a UI Evidence section. — N/A, no UI change.
• Public docs updated where needed (.env.example documents every new var).

Notes

• No migration, OpenAPI, or cf-typegen regeneration needed — docker-compose.yml/.env.example aren't scanned by any of those generators.

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.95%. Comparing base (06d3856) to head (e467e08).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

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  Files         399      399           
  Lines       36786    36786           
  Branches    13440    13440           
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  Hits        34561    34561           
  Misses       1569     1569           
  Partials      656      656           

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