fix(plugins): make hookify and plugin-dev agent frontmatter valid YAML

The description: field in these four agent files contained unquoted colon-space
sequences (Examples:, Context:, user:, assistant:) that strict YAML parsers
reject with "mapping values are not allowed in this context". Claude Code's
own parser tolerates this, but third-party tooling and linters fail on it.

Wraps each description in a |- literal block scalar with 2-space indentation
so the frontmatter is spec-compliant YAML. Description text and agent body are
byte-for-byte unchanged.

Same approach as #44055 (which covers pr-review-toolkit only).

Refs #40370

plugins/hookify/agents/conversation-analyzer.md

@@ -1,6 +1,13 @@
 ---
 name: conversation-analyzer
-description: Use this agent when analyzing conversation transcripts to find behaviors worth preventing with hooks. Examples: <example>Context: User is running /hookify command without arguments\nuser: "/hookify"\nassistant: "I'll analyze the conversation to find behaviors you want to prevent"\n<commentary>The /hookify command without arguments triggers conversation analysis to find unwanted behaviors.</commentary></example><example>Context: User wants to create hooks from recent frustrations\nuser: "Can you look back at this conversation and help me create hooks for the mistakes you made?"\nassistant: "I'll use the conversation-analyzer agent to identify the issues and suggest hooks."\n<commentary>User explicitly asks to analyze conversation for mistakes that should be prevented.</commentary></example>
+description: |-
+  Use this agent when analyzing conversation transcripts to find behaviors worth preventing with hooks. Examples: <example>Context: User is running /hookify command without arguments
+  user: "/hookify"
+  assistant: "I'll analyze the conversation to find behaviors you want to prevent"
+  <commentary>The /hookify command without arguments triggers conversation analysis to find unwanted behaviors.</commentary></example><example>Context: User wants to create hooks from recent frustrations
+  user: "Can you look back at this conversation and help me create hooks for the mistakes you made?"
+  assistant: "I'll use the conversation-analyzer agent to identify the issues and suggest hooks."
+  <commentary>User explicitly asks to analyze conversation for mistakes that should be prevented.</commentary></example>
 model: inherit
 color: yellow
 tools: ["Read", "Grep"]

plugins/plugin-dev/agents/agent-creator.md

@@ -1,6 +1,7 @@
 ---
 name: agent-creator
-description: Use this agent when the user asks to "create an agent", "generate an agent", "build a new agent", "make me an agent that...", or describes agent functionality they need. Trigger when user wants to create autonomous agents for plugins. Examples:
+description: |-
+  Use this agent when the user asks to "create an agent", "generate an agent", "build a new agent", "make me an agent that...", or describes agent functionality they need. Trigger when user wants to create autonomous agents for plugins. Examples:
 
   <example>
   Context: User wants to create a code review agent

plugins/plugin-dev/agents/plugin-validator.md

@@ -1,6 +1,7 @@
 ---
 name: plugin-validator
-description: Use this agent when the user asks to "validate my plugin", "check plugin structure", "verify plugin is correct", "validate plugin.json", "check plugin files", or mentions plugin validation. Also trigger proactively after user creates or modifies plugin components. Examples:
+description: |-
+  Use this agent when the user asks to "validate my plugin", "check plugin structure", "verify plugin is correct", "validate plugin.json", "check plugin files", or mentions plugin validation. Also trigger proactively after user creates or modifies plugin components. Examples:
 
   <example>
   Context: User finished creating a new plugin

plugins/plugin-dev/agents/skill-reviewer.md

@@ -1,6 +1,7 @@
 ---
 name: skill-reviewer
-description: Use this agent when the user has created or modified a skill and needs quality review, asks to "review my skill", "check skill quality", "improve skill description", or wants to ensure skill follows best practices. Trigger proactively after skill creation. Examples:
+description: |-
+  Use this agent when the user has created or modified a skill and needs quality review, asks to "review my skill", "check skill quality", "improve skill description", or wants to ensure skill follows best practices. Trigger proactively after skill creation. Examples:
 
   <example>
   Context: User just created a new skill