🔄 chore: update schema URL to v0.51.6 (#1549)

## Schema URL Update

Updates the MCP Gateway JSON schema validation URL from `v0.50.7` to
`v0.51.6`.

### Files Changed

- `internal/config/validation_schema.go` — `schemaURL` variable updated
to `v0.51.6`
- `internal/config/rules/rules.go` — `SchemaURL` constant updated to
`v0.51.6`
- `internal/config/validation_schema_test.go` — hardcoded schema URLs
updated to `v0.51.6`

### Why

Pinning to a specific release tag ensures reproducible, deterministic
configuration validation — the schema won't silently change between
runs.

### Release Notes

See the [gh-aw release
notes](https://github.com/github/gh-aw/releases/tag/v0.51.6) for changes
in this schema version.




> Generated by [Nightly Schema
Updater](https://github.com/github/gh-aw-mcpg/actions/runs/22597949790)

> [!WARNING]
> <details>
> <summary>⚠️ Firewall blocked 1 domain</summary>
>
> The following domain was blocked by the firewall during workflow
execution:
>
> - `invalidhostthatdoesnotexist12345.com`
>
> To allow these domains, add them to the `network.allowed` list in your
workflow frontmatter:
>
> ```yaml
> network:
>   allowed:
>     - defaults
>     - "invalidhostthatdoesnotexist12345.com"
> ```
>
> See [Network
Configuration](https://github.github.com/gh-aw/reference/network/) for
more information.
>
> </details>

> - [x] expires <!-- gh-aw-expires: 2026-03-09T22:15:16.286Z --> on Mar
9, 2026, 10:15 PM UTC

<!-- gh-aw-agentic-workflow: Nightly Schema Updater, engine: copilot,
id: 22597949790, workflow_id: nightly-schema-updater, run:
https://github.com/github/gh-aw-mcpg/actions/runs/22597949790 -->

<!-- gh-aw-expires-type: pull-request -->

<!-- gh-aw-workflow-id: nightly-schema-updater -->

Author: lpcox

internal/config/rules/rules.go

@@ -12,7 +12,7 @@ var log = logger.New("config:rules")
 // Documentation URL constants
 const (
 	ConfigSpecURL = "https://github.com/github/gh-aw/blob/main/docs/src/content/docs/reference/mcp-gateway.md"
-	SchemaURL     = "https://raw.githubusercontent.com/github/gh-aw/v0.50.7/docs/public/schemas/mcp-gateway-config.schema.json"
+	SchemaURL     = "https://raw.githubusercontent.com/github/gh-aw/v0.51.6/docs/public/schemas/mcp-gateway-config.schema.json"
 )
 
 // ValidationError represents a configuration validation error with context.

internal/config/validation_schema.go

@@ -41,7 +41,7 @@ var (
 	// Current schema version: v0.50.7
 	//
 	// Alternative: Embed the schema using go:embed directive for zero network dependency.
-	schemaURL = "https://raw.githubusercontent.com/github/gh-aw/v0.50.7/docs/public/schemas/mcp-gateway-config.schema.json"
+	schemaURL = "https://raw.githubusercontent.com/github/gh-aw/v0.51.6/docs/public/schemas/mcp-gateway-config.schema.json"
 
 	// Schema caching to avoid recompiling the JSON schema on every validation
 	// This improves performance by compiling the schema once and reusing it

internal/config/validation_schema_test.go

@@ -556,7 +556,7 @@ func TestEnhancedErrorMessages(t *testing.T) {
 				"Location:",
 				"Error:",
 				"Details:",
-				"https://raw.githubusercontent.com/github/gh-aw/v0.50.7/docs/public/schemas/mcp-gateway-config.schema.json",
+				"https://raw.githubusercontent.com/github/gh-aw/v0.51.6/docs/public/schemas/mcp-gateway-config.schema.json",
 			},
 		},
 		{