Publish capability: core.quote-with-caps (formula pricing quote with hard caps)

## Why

`core.calculate-price` covers line × unit_price + optional discount/tax. Quoting engines also need **hard min/max caps and simple formula knobs** (e.g. base + per-unit, then clamp) so an agent cannot invent an uncapped price. This is a small, deterministic **quote-with-caps** companion — not a rewrite of `core.calculate-price`.

## One-PR ask

Publish **`core.quote-with-caps@1.0.0`**:

**Inputs:**
- `quantity`: number (≥ 0)
- `formula`: `{ "base": number, "per_unit": number, "currency": string }` (currency code string; no FX)
- `caps`: `{ "min_total"?: number, "max_total"?: number }` (if both set, require min ≤ max or fail closed)
- `config_version`: string

**Outputs:**
- `currency`: string
- `subtotal`: number (base + quantity * per_unit, before clamp)
- `total`: number (after clamp)
- `capped`: boolean
- `cap_applied`: `"none"|"min"|"max"`
- `config_version`: string
- `ok`: boolean
- `reason_code`: enum e.g. `ok` | `invalid_quantity` | `invalid_caps` | `invalid_formula`

**Behavior:** Deterministic arithmetic. Document rounding (e.g. round half-even to 2 decimal places for money-like numbers, or integer millis — pick one and lock tests). No tax/discount matrix (that's `core.calculate-price`).

Follow [`CONTRIBUTING.md`](https://github.com/traverse-framework/registry/blob/main/CONTRIBUTING.md) and [`capabilities/README.md`](https://github.com/traverse-framework/registry/blob/main/capabilities/README.md) publish checklist.

- Include `capability-src/` with real Rust tests meeting registry coverage gates (`functions` 100%, lines/regions ≥ 95%)
- Use `traverse-cli capability publish` (or the documented scaffold) so `artifact.digest` / `artifact.url` survive
- Declare `authoring.method` (`human` or `llm-assisted`)
- Ensure every `use_cases[].persona_ref` resolves (scaffold personas if needed)
- Run `bash scripts/ci/pre_pr_check.sh ` before opening
- One capability per PR; branch from `origin/main`, not another `publish/*` branch

**Apps are not ready — publish the capability only.** No app wiring, no demo product surface.

## Out of scope

- Full discount/tax engines (use / extend patterns from `core.calculate-price` instead)
- FX conversion, coupon catalogs, or cart state
- Host-persisted pricing config (`commerce.pricing-config` already exists)

## Done when

- CI green; published in next index
- Tests: uncapped, hit min, hit max, invalid caps fail closed, quantity 0

## Host / deps notes

**Pure WASM.** No connector, no network. Distinct id from `core.calculate-price`.

## Labels

`help wanted` · `good first issue` · `enhancement` · `no-spec-needed`

Read CONTRIBUTING.md, capabilities/README.md, and the existing core.calculate-price patterns first. Use the documented scaffold or traverse-cli capability publish, add capability-src/ with Rust tests for uncapped, minimum, maximum, invalid-cap, and zero-quantity cases, and lock the chosen rounding behavior in tests. Run bash scripts/ci/pre_pr_check.sh against the draft PR body and confirm the published artifact metadata and persona references pass the registry checks.

Written by the indexing model from the issue text.