Rewrite store JSDoc, split quote/order into modules, and generate typed API docs

- Rewrite JSDoc across all store methods to document the actual async
  methods (real params, returns, throws) instead of the internal wrappers
- Split quote/order into individual module files backed by shared
  manifestDoc helpers; remove the createStore factory and thin wrappers
- Deduplicate manifest line helpers into src/store/manifestLines.js
- Extend generate-api-doc.js to render parameter/return/throws types and
  emit per-namespace API.<module>.md files with an API.md index
- Regenerate all API docs

API.tax.md

@@ -8,6 +8,19 @@ This document is auto-generated from the JSDoc comments in `src/store` by runnin
 
 Creates a new tax rate.
 
+**Parameters**
+
+| Name | Type | Description |
+| --- | --- | --- |
+| `rate` | `number` | The tax rate in percent (e.g. `19`). |
+| `[tx]` | `object` | Optional transaction to run within. |
+
+**Returns**
+
+`Promise<number>` — The id of the created tax rate.
+
+**Example**
+
 ```js
 const id = await store.tax.create(19);
 // => 1
@@ -19,6 +32,19 @@ const id = await store.tax.create(19);
 
 Returns the id of a tax rate, creating it if it does not exist.
 
+**Parameters**
+
+| Name | Type | Description |
+| --- | --- | --- |
+| `rate` | `number` | The tax rate in percent (e.g. `19`). |
+| `[tx]` | `object` | Optional transaction to run within. |
+
+**Returns**
+
+`Promise<number>` — The id of the tax rate.
+
+**Example**
+
 ```js
 const id = await store.tax.ensure(19);
 // => 1
@@ -30,6 +56,19 @@ const id = await store.tax.ensure(19);
 
 Returns a tax row by its rate.
 
+**Parameters**
+
+| Name | Type | Description |
+| --- | --- | --- |
+| `rate` | `number` | The tax rate in percent (e.g. `19`). |
+| `[tx]` | `object` | Optional transaction to run within. |
+
+**Returns**
+
+`Promise<{id: number, rate: number}>` — The tax row, or `undefined` if not found.
+
+**Example**
+
 ```js
 const tax = await store.tax.getByRate(19);
 // => { id: 1, rate: 19 }
@@ -41,6 +80,12 @@ const tax = await store.tax.getByRate(19);
 
 Lists all tax rates.
 
+**Returns**
+
+`Promise<Array<{id: number, rate: number}>>` — All tax rate rows.
+
+**Example**
+
 ```js
 const taxes = await store.tax.list();
 // => [{ id: 1, rate: 19 }]