docs: align the hand-written plugin docs with the ADR-0049 retirements (#11982, #12587)

Docs-drift pass over the six pages the drift bot anchored to this diff:

- plugins/anatomy.mdx: the Plugin-class example carried the retired
  configSchema field with a comment claiming the loader validates it; the
  block now shows constructor-owned config and names the retirement
- plugins/index.mdx: the Configuration Validation bullet and the configSchema
  half of the securePlugin example removed (signature kept - live surface);
  replacement paragraph states the plugin-owned self-parse pattern
- protocol/kernel/index.mdx: the Configuration Management snippet and the
  fail-fast callout no longer document the retired field as merely
  'postponed' - both now state the retirement and the self-parse seam

No change, with the reason measured per page: automation/flows.mdx names the
ADR-0018 node-executor configSchema (different surface);
getting-started/quick-reference.mdx names spec's plugin-validator.zod.ts
PluginMetadata (locally-declared homonym, live);
protocol/kernel/plugin-spec.mdx teaches the surviving self-parse pattern -
its phantom manifest file-map row predates this diff and is filed as #12690.
content/docs/releases/v17.mdx is release-owned and untouched; its four
configSchema mentions are all the ADR-0018 / driver surfaces, none the
kernel field.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LZbWd2jNV1FErXTPSS4Dry

Author: claude

content/docs/plugins/anatomy.mdx

@@ -9,7 +9,6 @@ Plugins are the building blocks of ObjectStack. A plugin is a plain JavaScript/T
 
 ```typescript
 import type { Plugin, PluginContext } from '@objectstack/core';
-import { z } from 'zod';
 
 export class MyPlugin implements Plugin {
     // Identity
@@ -21,12 +20,12 @@ export class MyPlugin implements Plugin {
     // This controls init ordering — it is NOT an npm-style version map.
     dependencies = ['com.objectstack.engine.objectql'];
 
-    // Configuration Schema (Optional)
-    // Read by the plugin loader to validate config; it lives on the plugin
-    // metadata rather than the base `Plugin` interface.
-    configSchema = z.object({
-        apiKey: z.string()
-    });
+    // Configuration (Optional)
+    // A plugin owns its config: take it as a constructor/factory argument and
+    // parse it yourself (with a Zod schema, say) before use. The kernel never
+    // receives plugin config — the old `configSchema` metadata field was
+    // retired under ADR-0049 because nothing could ever run it.
+    constructor(private readonly options: { apiKey?: string } = {}) {}
 
     /**
      * Init Phase (REQUIRED)

content/docs/plugins/index.mdx

@@ -284,22 +284,21 @@ const dbPlugin: PluginMetadata = {
 
 ObjectStack supports plugin security features:
 
-- **Configuration Validation**: Plugins can define a Zod `configSchema` for runtime validation
 - **Signature Verification**: Cryptographic signatures for plugin integrity
 - **Permission Enforcement**: Fine-grained access control for plugin operations
 
-```typescript
-import { z } from 'zod';
+Plugin configuration is the plugin's own concern: take it as a constructor or
+factory argument and parse it at your own seam (a Zod `schema.parse` in the
+factory, constructor or `init`). The kernel-side `configSchema` metadata field
+was retired under ADR-0049 — the kernel never received a plugin's config, so
+the field could not validate anything.
 
+```typescript
 const securePlugin: PluginMetadata = {
   name: 'com.example.secure',
   version: '1.0.0',
-  configSchema: z.object({
-    apiKey: z.string().min(1),
-    region: z.enum(['us', 'eu', 'ap']),
-  }),
   signature: 'ed25519:key-1:<base64url-signature>',
-  
+
   async init(ctx) { /* ... */ },
 };
 ```

content/docs/protocol/kernel/index.mdx

@@ -403,20 +403,14 @@ packages/plugins/plugin-slack-integration/
 
 ### Configuration Management
 ```typescript
-// A plugin object may carry a Zod `configSchema` describing its settings.
-// NOTE: the kernel RECORDS the schema but does not enforce it yet — `use()`
-// takes no config argument, so the loader has nothing to parse and logs
-// "config validation postponed" instead of running the schema. Treat
-// `configSchema` as a declaration of shape, and validate values you actually
-// depend on yourself.
+// A plugin owns its config: `use()` takes no config argument and the kernel
+// never receives one, so validate the values you depend on at your own seam
+// (a Zod `schema.parse` in the plugin's factory, constructor or `init`).
+// The old `configSchema` metadata field was retired under ADR-0049 — the
+// loader only ever logged "config validation postponed" and returned.
 export const slackPlugin: Plugin = {
   name: 'slack-integration',
   version: '0.1.0',
-  configSchema: z.object({
-    apiKey: z.string().describe('Slack API Key'),
-    channel: z.string().default('#general'),
-    enabled: z.boolean().default(true),
-  }),
   async init(ctx) {
     // Runtime-resolved values come from the `settings` service, not from a
     // `config` object on the context — there is no `ctx.config`.
@@ -487,10 +481,11 @@ const message = i18n.t('slack.button.send', context.locale);
 **Example:** Wiring, not config, is what the kernel currently enforces at boot. A plugin that declares a dependency the kernel never received fails `bootstrap()` outright — `[Kernel] Dependency 'com.objectstack.engine.objectql' not found for plugin 'com.objectstack.audit'` — and a dependency cycle throws `[Kernel] Circular dependency detected: <plugin>`. Boot stops there instead of a request failing later.
 
 <Callout type="warn">
-  Plugin `configSchema` is **not** part of this fail-fast path yet. The loader
-  stores the schema and postpones the check, so a missing or malformed value in
-  a plugin's config will not stop boot today. Validate config you depend on in
-  your own `init`.
+  Plugin config is **not** part of this fail-fast path. The old `configSchema`
+  metadata field was retired under ADR-0049 — the loader never enforced it —
+  so a missing or malformed value in a plugin's config will not stop boot.
+  Parse config you depend on yourself, in your plugin's factory, constructor
+  or `init`.
 </Callout>
 
 ## Comparison: Kernel vs Alternatives