feat: wire closed-loop production consumers (Phase J)

[psdjungpulzze]

Phase J — Wire Production Consumers (Final Phase)

The substrate's read side has `applyCostCalibration`, `getThreshold`, and `getCalibration` helpers ready, but no production code calls them yet. This PR wires the three remaining consumers so every loop actually steers behavior:

Wiring	Consumer	Producer feeds it
J1 Cost forecast	`budget.ts:checkMonthlyBudget` corrects its monthly extrapolation via `applyCostCalibration`	`calibrate-predictors` (Phase G)
J2 Auto-flag severity	`imports/[importId]/commit` auto-flag block consults `getThreshold("flag-auto:")` and uses the multiplier to upgrade or downgrade per-tenant	`tune-thresholds` (Phase H)
J3 Digest engagement	`run-daily-digest` skips users whose engagement-rate calibration is below a floor	`tune-engagement` (Phase I)

Depends on: #33 (Phase I — engagement). Branched off Phase I.

Cold-start safety preserved end-to-end

• `LOOPS_ENABLED !== "true"` → all three consumers fall through to today's behavior
• No calibration/threshold present → identity transform / hardcoded baseline
• Substrate read fails → warn-log + cold-start fallback

Test plan

• J1: budget.ts test — forecast corrected by calibration
• J2: import-commit test — severity multiplied by threshold
• J3: run-daily-digest test — low-engagement user skipped
• `npm run typecheck` clean
• `npm test` — no new failures vs. Phase I baseline

Final state

After this PR every archetype has full producer + storage + learning + production consumer. The closed-loop architecture is end-to-end functional.

[psdjungpulzze]

Closing without changes. After review the Phase J wirings (cost calibration into budget, threshold-tuned auto-flag severity, engagement-based digest suppression) all involve user-visible behavior changes whose risk/reward doesn't favor speculative wiring. The substrate-side helpers (applyCostCalibration, getThreshold, getCalibration(\"engagement-rate:*\")) are ready in the merged Phases G/H/I — pick them up in a focused PR when there's a concrete operator or user trigger.