Add generic config property bag to HookConfig

[wbreza]

Background & Motivation

Different hook executor types (Python, JS, TS, .NET) have unique configuration needs beyond the shared run, dir, kind, and continueOnError fields. Today there's no mechanism for users to pass executor-specific settings in azure.yaml.

azd already uses a config property bag pattern in several places:

• state.RemoteConfig — backend discriminator + Config map[string]any for backend-specific settings
• platform.Config — type discriminator + Config map[string]any for platform-specific settings
• ServiceConfig — Config map[string]any for service-target-specific settings (e.g., packageManager for Node.js)

Proposal

Add a Config map[string]any field to HookConfig in pkg/ext/models.go, discriminated by the existing Kind field. Each executor receives the raw config bag and can unmarshal it into a strongly-typed struct.

Example azure.yaml

hooks:
  postprovision:
    run: ./hooks/seed-database.cs
    kind: dotnet
    config:
      configuration: Release
      framework: net10.0

hooks:
  postprovision:
    run: ./hooks/setup.py
    kind: python
    config:
      virtualEnvName: .venv

Implementation Approach

1. Add Config map[string]any to HookConfig (yaml tag: config,omitempty)
2. Extend ExecutionContext to carry the raw config bag to executors
3. Each executor optionally unmarshals the config bag into a typed struct (e.g., dotnetHookConfig{Configuration string, Framework string}) using mapstructure or encoding/json re-marshal
4. Update the JSON schema (azure.yaml.json) — use a oneOf discriminated on kind to validate per-executor config shapes
5. Update docs/language-hooks.md with per-executor config options

Example Executor Config Types

// dotnet executor
type dotnetHookConfig struct {
    Configuration string `json:"configuration"` // Debug, Release
    Framework     string `json:"framework"`     // net8.0, net10.0
}

// python executor
type pythonHookConfig struct {
    VirtualEnvName string `json:"virtualEnvName"` // override venv dir name
}

Out of Scope

• Config validation at YAML load time (executors validate their own config)
• Config inheritance from project-level to service-level hooks

Related

• Parent Epic: Multi-Language Hook Support: Python, JavaScript, TypeScript, .NET #7435 — Multi-Language Hook Support
• PR feat: implement C#/.NET hook executor #7652 — .NET hook executor (initial implementation without config bag)