Clean and update documentation

docs/consumers/pkg-model.md

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+# Package `model`
+
+## Import Path
+
+```go
+import "gitea.maximumdirect.net/ejr/weatherfeeder/model"
+```
+
+## Purpose
+
+Package `model` defines `weatherfeeder`'s canonical weather payload structs.
+These structs are emitted as the `payload` of canonical `weather.*.v1` events
+and are also the domain types consumed by downstream applications such as
+`weatherapi`.
+
+The JSON field tags on these structs are part of the wire contract. For the full
+field-by-field JSON contract, use the [event wire contract](../integrations/events.md).
+
+## Payload Types
+
+Current canonical schema families map to these public types:
+
+| Schema | Primary type |
+|---|---|
+| `weather.observation.v1` | `WeatherObservation` |
+| `weather.forecast.v1` | `WeatherForecastRun` |
+| `weather.forecast_discussion.v1` | `WeatherForecastDiscussion` |
+| `weather.weather_story.v1` | `WeatherStoryRun` |
+| `weather.alert.v1` | `WeatherAlertRun` |
+| `weather.outlook.v1` | `WeatherOutlookRun` |
+
+Related child types include:
+
+- `WeatherObservationPresentWeather`
+- `WeatherForecastPeriod`
+- `WeatherForecastDiscussionSection`
+- `WeatherStory`
+- `WeatherAlert`
+- `WeatherAlertReference`
+- `WeatherOutlook`
+- `WMOCode`
+
+## Wire And Compatibility Rules
+
+- JSON tags define canonical payload field names.
+- Pointer fields and fields tagged `omitempty` are optional on the wire.
+- Missing optional fields mean unknown or not applicable.
+- Canonical measurements use metric units.
+- Canonical timestamps are `time.Time` values encoded by Go's JSON encoder.
+- Normalized canonical timestamps are UTC unless a field-specific contract says
+  otherwise.
+- Additive fields are compatible within a schema version.
+- Removing, renaming, or changing the meaning of a field requires a new schema
+  identifier.
+
+## Boundaries
+
+`model` should not depend on source adapters, sinks, SQL column names, provider
+HTTP shapes, or runtime configuration.
+
+Consumers should not rely on packages under `internal/...`. Use `model` with
+schema constants from [`standards`](pkg-standards.md) and the JSON contract in
+[`docs/integrations/events.md`](../integrations/events.md).