docs: expand agent and tool documentation with detailed descriptions

agents/README.md:
- Added detailed descriptions for Explore, Plan, and Task agents
- Documented capabilities, when to use, and tools available
- Added utilities/ section for shared prompts

tools/README.md:
- Added detailed descriptions for file, shell, and search tools
- Documented key parameters and behaviors
- Added security notes for bash/sandbox

agents/utilities/:
- todowrite-prompt.md - Task list management
- askuserquestion-prompt.md - User clarification
- conversation-summarization-prompt.md - Context compaction
- session-title-prompt.md - Title/branch generation
- security-review-prompt.md - Security analysis

Source: gitea:library/claude-code-system-prompts

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/domains/agents/utilities/README.md

@@ -0,0 +1,64 @@
+# Agent Utilities
+
+Reference prompts for utility functions used across agents.
+
+## Prompts
+
+### todowrite-prompt.md
+**Purpose:** Task list management for tracking progress.
+
+Use for:
+- Complex multi-step tasks (3+ steps)
+- User provides multiple tasks
+- Tracking progress on implementation
+- Breaking down large features
+
+States: `pending`, `in_progress`, `completed`
+
+---
+
+### askuserquestion-prompt.md
+**Purpose:** Interactive clarification during execution.
+
+Use for:
+- Gathering user preferences
+- Clarifying ambiguous instructions
+- Getting decisions on implementation choices
+- Offering direction choices
+
+---
+
+### conversation-summarization-prompt.md
+**Purpose:** Compacting long conversations for context management.
+
+Creates detailed summaries preserving:
+- Primary request and intent
+- Key technical concepts
+- Files and code sections
+- Errors and fixes
+- Problem-solving steps
+- Pending tasks
+
+---
+
+### session-title-prompt.md
+**Purpose:** Generate concise session titles and git branch names.
+
+Output format:
+- Title: 3-6 words, no quotes
+- Branch: kebab-case, 2-4 words (e.g., `add-user-auth`)
+
+---
+
+### security-review-prompt.md
+**Purpose:** Comprehensive security analysis of code changes.
+
+Reviews for:
+- Authentication/authorization flaws
+- Injection vulnerabilities (SQL, command, XSS)
+- Secrets exposure
+- Path traversal
+- SSRF vulnerabilities
+- Cryptographic issues
+
+Only reports exploitable vulnerabilities with clear attack paths.