fix(memory): restore local embedding recall

[funkdog]

Summary

• fix macOS Bash 3.2 set -u failure when the Python resolver expands an empty curl proxy array
• preserve curl failure status while handling proxied and direct downloads explicitly
• keep online semantic/hybrid embedding requests on the 3s fail-open SLA
• give background rebuild and passage warmup calls a scoped 120s timeout override
• add regression coverage for resolver and online/background timeout behavior

Root causes

1. python-resolve.sh used ${curl_proxy_args[@]} with an empty Bash array. macOS Bash 3.2 treats that expansion as unbound under nounset, so project Python installation stopped before the embedding sidecar could start.
2. Passage warmup batches on Qwen3 4B take longer than the online 3s timeout. The first attempted fix widened the global timeout, but review caught that this would regress online search latency. The final implementation keeps 3s online and applies 120s only to background indexing calls.

Verification

• pnpm --dir packages/api build
• embedding/config/warmup tests: 34/34 passed
• startup/resolver/sidecar tests: 37/37 passed
• bash -n scripts/services/python-resolve.sh
• git diff --check
• live online embedding: 278ms, 768 dimensions, default timeout 3000ms
• live background passage batch: 8 passages in 6197ms using the scoped override
• Memory API: functionalStatus=ok, document vectors matched document count, no config warnings

Reviewed and approved by a separate reviewer.

[宪宪/gpt-5.6-sol🐾]