Add JSON schema generation/validation and structured configuration diagnostics

Buildvana.slnx

@@ -42,6 +42,7 @@
     <Project Path="src/Buildvana.Core.ConsoleOutput/Buildvana.Core.ConsoleOutput.csproj" />
     <Project Path="src/Buildvana.Core.HomeDirectory/Buildvana.Core.HomeDirectory.csproj" />
     <Project Path="src/Buildvana.Core.Json/Buildvana.Core.Json.csproj" />
+    <Project Path="src/Buildvana.Core.JsonSchema/Buildvana.Core.JsonSchema.csproj" />
     <Project Path="src/Buildvana.Core.Process/Buildvana.Core.Process.csproj" />
     <Project Path="src/Buildvana.Sdk.SourceGenerators/Buildvana.Sdk.SourceGenerators.csproj" />
     <Project Path="src/Buildvana.Sdk.Tasks/Buildvana.Sdk.Tasks.csproj" />
@@ -50,6 +51,8 @@
   </Folder>
   <Folder Name="/tests/">
     <File Path="tests/Common.targets" />
+    <Project Path="tests/Buildvana.Core.Configuration.Tests/Buildvana.Core.Configuration.Tests.csproj" />
+    <Project Path="tests/Buildvana.Core.JsonSchema.Tests/Buildvana.Core.JsonSchema.Tests.csproj" />
     <Project Path="tests/Buildvana.Tool.Tests/Buildvana.Tool.Tests.csproj" />
   </Folder>
 </Solution>

docs/ToolDiagnostics.md

@@ -0,0 +1,30 @@
+# Diagnostics issued by `bv`
+
+<!-- markdownlint-disable MD036 -->
+**Table of contents**
+<!-- markdownlint-enable MD036 -->
+
+- [Overview](#overview)
+- [Main program (1000-1099)](#main-program-1000-1099)
+- [Configuration (1100-1199)](#configuration-1100-1199)
+
+## Overview
+
+All diagnostics issued by the `bv` CLI tool have a `BV` prefix. All numbers start from 1000, so there are no leading zeros.
+
+Each part of the program is assigned a contiguous range of 100 diagnostics, as listed below. The first range is reserved for the main program.
+
+## Main program (1000-1099)
+
+There are no associated diagnostics.
+
+## Configuration (1100-1199)
+
+| Code   | Severity | Message                                               | Description                                                                                                                                  |
+| ------ | :------: | ----------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
+| BV1100 |  Error   | _(the JSON parser's reason)_                          | The configuration file could not be parsed as JSON. The message carries the parser's reason; the location points at the offending character. |
+| BV1101 |  Error   | Expected _(type)_, but found _(type)_.                | A value has a type the schema does not allow at that location (for example, a number where a string is required, or an explicit `null`).     |
+| BV1102 |  Error   | _(value)_ is not one of the allowed values: _(list)_. | A value is not among those the schema permits at that location (for example, an unknown enumeration value).                                  |
+| BV1103 |  Error   | Unknown property '_(name)_'.                          | The configuration file contains a property the schema does not define, or a dictionary key outside the allowed set.                          |
+| BV1104 |  Error   | Missing required property '_(name)_'.                 | A property the schema marks as required is absent.                                                                                           |
+| BV1105 |  Error   | No value is allowed here.                             | A value appears at a location where the schema permits none.                                                                                 |