feat: add full economics modeling for IntelIP scenarios

[hudsonaikins]

Summary

• add full-economics cost-layer modeling and reporting across CLI, JSON, markdown, and simulation output
• support IntelIP scenario packs for conservative, target, stress, paid-pilot, tight-free, and workspace-minimum rollout analysis
• extend pricing/config/cost validation and tests for mix pricing, workspace-hybrid pricing, paid-user-scoped costs, and related regression fixtures

Testing

• go test ./...

Greptile Summary

This PR adds a full-economics cost-layer model (delivery / productization / adoption) to ProfitCtl, extending the config schema, cost engine, simulation, and all output surfaces (CLI, JSON, Markdown). It also ships a complete IntelIP scenario pack — six YAML files covering conservative, target, stress, paid-pilot, tight-free, and workspace-minimum rollout shapes — together with calibration notes and a tooling cost inventory.

• P1 – Four mix-mode scenario files cannot be parsed: intelip_ops_conservative.yml, intelip_ops_target.yml, intelip_ops_stress.yml, and intelip_rollout_tight_free.yml all include limits.users on their plans. validateMixPricing explicitly rejects any plan with a non-nil Limits in mix mode, so ParseConfig returns a validation error for each of these files. The two workspace-hybrid scenarios are unaffected.
• P2 – Potential double-counting in FullEconomicsSummary: buildFullEconomicsSummary adds paymentFees.Total to both DeliveryCost and TotalCost. If a future config combines a payment_fees: YAML block with a user_scope: paid_users variable cost for the same fee, the amount is counted twice. The current scenario files avoid this by using only the variable-cost approach, but the risk is undocumented.

Confidence Score: 4/5

Safe to merge after fixing the mix-mode limits validation conflict that blocks four of the six new scenario files.

The Go engine changes are clean and well-tested. One P1 defect blocks the primary user-facing deliverable of this PR (running the IntelIP scenario pack): four mix-mode YAML files include limits that the validator rejects. This needs to be resolved before the scenario files are usable.

The four mix-mode scenario files (intelip_ops_conservative.yml, intelip_ops_target.yml, intelip_ops_stress.yml, intelip_rollout_tight_free.yml) and internal/config/validator.go (the validateMixPricing function).

Important Files Changed

Filename	Overview
benchmark_scenarios/intelip_ops_conservative.yml	New IntelIP conservative scenario; includes limits on mix-mode plans which the validator rejects — the file cannot be parsed/run as-is.
benchmark_scenarios/intelip_ops_target.yml	New IntelIP target scenario; same limits-in-mix-mode validation failure as conservative.
benchmark_scenarios/intelip_ops_stress.yml	New IntelIP stress scenario; same limits-in-mix-mode validation failure.
benchmark_scenarios/intelip_rollout_tight_free.yml	New tight-free rollout scenario; same limits-in-mix-mode validation failure.
internal/config/validator.go	Adds validateMixPricing, validateWorkspaceHybridPricing, and validatePricingPlanCohort; the mix validator explicitly rejects limits on plans, which conflicts with the new scenario files.
cmd/simulation_runner.go	Adds buildFullEconomicsSummary helper and wires cfg.Pricing into scale/stress simulation calls; potential double-counting of payment fees when both variable-cost and payment_fees section are used together.
internal/output/json.go	Adds pointer-guarded full_economics block to JSON output; populated only when TotalCost > 0.
pkg/types/cost.go	Introduces EconomicsLayer, EconomicsAllocationMode, VariableCostUserScope types with backward-compatible normalization helpers; well-structured.
pkg/types/structures.go	Extends FixedCost and VariableCost with EconomicsLayer and Allocation; adds EconomicsLayerBreakdown with Add and Round helpers.
internal/pricing/calculator.go	Adds calculateMixRevenue and calculateWorkspaceHybridRevenue; share allocation with deterministic rounding is correct.

Prompt To Fix All With AI

This is a comment left during a code review.
Path: benchmark_scenarios/intelip_ops_conservative.yml
Line: 226-264

Comment:
**`limits` in `mix` mode fails validation**

`validateMixPricing` in `internal/config/validator.go` (line ~228) explicitly rejects any plan that has a non-nil `Limits` field:

```go
if plan.Limits != nil {
    return fmt.Errorf("pricing mode mix does not support limits on plan %s: %w", …)
}
```

All four new `mix`-mode YAML scenario files (`conservative`, `target`, `stress`, `tight_free`) include a `limits.users` block on every plan. Calling `ParseConfig` on any of them returns a validation error — so `go run . simulate -f benchmark_scenarios/intelip_ops_conservative.yml` (and the equivalent for the other three) will fail immediately, regardless of the comment in `intelip_ops_pricing_pack.md` that says "`limits.users` can still be carried for reference."

Fix options:
1. **Remove the `limits` blocks** from the four scenario files (they are ignored by `calculateMixRevenue` anyway), or
2. **Relax the validator** to allow `limits` in `mix` mode when a `share` is also present, treating them as documentation metadata only.

How can I resolve this? If you propose a fix, please make it concise.

---

This is a comment left during a code review.
Path: cmd/simulation_runner.go
Line: 1271-1289

Comment:
**Payment fees double-counted when both sources are active**

`buildFullEconomicsSummary` adds `paymentFees.Total` to both `DeliveryCost` and `TotalCost`:

```go
DeliveryCost: totalCosts.GrandByEconomicsLayer.Delivery + paymentFees.Total,
TotalCost:    totalCosts.GrandTotal + paymentFees.Total,
```

`totalCosts.GrandTotal` already includes variable costs whose `economics_layer` defaults to `delivery` — and the new scenario files model Stripe fees exactly this way (a `user_scope: paid_users` variable cost). If a future config combines that variable-cost approach with a `payment_fees:` YAML block, `paymentFees.Total` would add the structured fee on top of the variable cost that already covers it, inflating both `DeliveryCost` and `TotalCost`.

Consider documenting that these two mechanisms are mutually exclusive for payment-fee modeling, or add a guard in `buildFullEconomicsSummary` that only adds `paymentFees.Total` when the variable costs do not already contain a `paid_users`-scoped fee line.

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (2): Last reviewed commit: "chore: address PR cleanup feedback" | Re-trigger Greptile}