perf(core): parallelize resolveTier's independent storage reads

[pedrofrxncx]

Source: storage-ports latency-investigation hunt (issue #2995 — "DB latency amplifies significantly across MCP tool calls"). resolveTier (apps/api/src/core/resolve-tier.ts) is on the model-resolution path for interactive chat and every automation/task-board/review-judge call that picks a tier — it runs on essentially every agent turn.

Payoff: the function issued three independent DB reads back-to-back with await: org settings, the per-user model-preference override, and the AI provider key list. None of the three depends on another's result, so serializing them adds up to two extra round-trips of latency to every tier resolution for no reason. This change fetches all three concurrently with Promise.all, same conditional skip for the user-prefs read (still not issued when applyUserPrefs is off).

Behavior: unchanged — same three conditions gate the user-prefs read, same values feed orgSlot/userSlot/keys afterward, only the await ordering changed from serial to parallel.

How a reviewer confirms: run bun test apps/api/src/core/resolve-tier.test.ts (all 10 cases still pass, including the one asserting userModelPreferences.get is NOT called when applyUserPrefs is unset).

Checks run locally: bun run fmt, cd apps/api && bunx tsc --noEmit (clean), bun test apps/api/src/core/resolve-tier.test.ts (10/10 pass), bunx oxlint apps/api/src/core/resolve-tier.ts (0 warnings/errors). Full CI validates the rest.

---

Summary by cubic

Parallelizes resolveTier’s independent storage reads to reduce per-turn latency in model resolution. Previously, org settings, user model preferences (conditionally), and AI provider keys were read sequentially; they now load in parallel with unchanged behavior, including skipping the user-preferences read when it does not apply. This supports issue #2995 on DB latency across MCP tool calls.

• Review notes
  • The gating for user preferences is unchanged: it applies only when applyUserPrefs is set, the tier is a chat tier, and a userId exists; the read is skipped otherwise.
  • Run tests: bun test apps/api/src/core/resolve-tier.test.ts (ensures the skip behavior and overall resolution logic remain intact).
  • No API or schema changes; no migration or config updates required.

^{Written for commit f1f9afa. Summary will update on new commits.}