docs: Update all documentation to reflect v5.4.0 skill-based search

Documentation Updates:
- README.md: Updated version badge, What's New, and search section
- docs/usage/search-tools.mdx: Rewrote for skill-based natural language approach
- docs/architecture/mcp-search.mdx → search-architecture.mdx: Complete rewrite
- docs/architecture/overview.mdx: Updated components and search pipeline
- docs/usage/getting-started.mdx: Added skill-based search section
- docs/configuration.mdx: Updated search configuration for v5.4.0
- docs/introduction.mdx: Updated key features
- docs/docs.json: Updated navigation to search-architecture

Key Changes:
- Emphasized ~2,250 token savings per session start
- Converted all examples to natural language queries
- Documented 10 HTTP API endpoints
- Explained progressive disclosure pattern
- Added migration notes (transparent, no user action required)
- Removed outdated MCP references

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

docs/architecture/overview.mdx

@@ -10,9 +10,9 @@ description: "System components and data flow in Claude-Mem"
 Claude-Mem operates as a Claude Code plugin with five core components:
 
 1. **Plugin Hooks** - Capture lifecycle events (7 hook files)
-2. **Worker Service** - Process observations via Claude Agent SDK
-3. **Database Layer** - Store sessions and observations (SQLite + FTS5)
-4. **MCP Search Server** - Query historical context (9 search tools)
+2. **Worker Service** - Process observations via Claude Agent SDK + HTTP API (10 search endpoints)
+3. **Database Layer** - Store sessions and observations (SQLite + FTS5 + ChromaDB)
+4. **Search Skill** - Skill-based search with progressive disclosure (v5.4.0+)
 5. **Viewer UI** - Web-based real-time memory stream visualization
 
 ## Technology Stack
@@ -44,16 +44,19 @@ Hook (stdin) → Database → Worker Service → SDK Processor → Database →
 4. **Output**: Processed summaries written back to database
 5. **Retrieval**: Next session's context hook reads summaries from database
 
-### Search Pipeline
+### Search Pipeline (v5.4.0+)
 ```
-Claude Request → MCP Server → SessionSearch Service → FTS5 Database → Search Results → Claude
+User Query → Skill Invoked → HTTP API → SessionSearch Service → FTS5 Database → Search Results → Claude
 ```
 
-1. **Query**: Claude uses MCP search tools (e.g., `search_observations`)
-2. **Search**: MCP server calls SessionSearch service with query parameters
-3. **FTS5**: Full-text search executes against FTS5 virtual tables
-4. **Format**: Results formatted as `search_result` blocks with citations
-5. **Return**: Claude receives citable search results for analysis
+1. **User Query**: User asks naturally: "What bugs did we fix?"
+2. **Skill Invoked**: Claude recognizes intent and invokes search skill
+3. **HTTP API**: Skill uses curl to call HTTP endpoint (e.g., `/api/search/observations`)
+4. **SessionSearch**: Worker service queries FTS5 virtual tables
+5. **Format**: Results formatted and returned to skill
+6. **Return**: Claude presents formatted results to user
+
+**Token Savings**: ~2,250 tokens per session vs MCP approach through progressive disclosure
 
 ## Session Lifecycle
 
@@ -110,9 +113,6 @@ claude-mem/
 │   │   ├── summary-hook.ts     # Stop
 │   │   └── cleanup-hook.ts     # SessionEnd
 │   │
-│   ├── servers/                # MCP servers
-│   │   └── search-server.ts    # MCP search tools server (9 tools)
-│   │
 │   ├── sdk/                    # Claude Agent SDK integration
 │   │   ├── prompts.ts          # XML prompt builders
 │   │   ├── parser.ts           # XML response parser
@@ -146,7 +146,6 @@ claude-mem/
 ├── plugin/                     # Plugin distribution
 │   ├── .claude-plugin/
 │   │   └── plugin.json
-│   ├── .mcp.json               # MCP server configuration
 │   ├── hooks/
 │   │   └── hooks.json
 │   ├── scripts/                # Built executables
@@ -157,8 +156,14 @@ claude-mem/
 │   │   ├── save-hook.js
 │   │   ├── summary-hook.js
 │   │   ├── cleanup-hook.js
-│   │   ├── worker-service.cjs  # Background worker
-│   │   └── search-server.mjs   # MCP search server
+│   │   └── worker-service.cjs  # Background worker + HTTP API
+│   │
+│   ├── skills/                 # Agent skills (v5.4.0+)
+│   │   ├── search/             # Search skill with progressive disclosure
+│   │   │   ├── SKILL.md        # Skill frontmatter (~250 tokens)
+│   │   │   └── operations/     # Detailed operation docs
+│   │   ├── troubleshoot/       # Troubleshooting skill
+│   │   └── version-bump/       # Version management skill
 │   │
 │   └── ui/                     # Built viewer UI
 │       └── viewer.html         # Self-contained bundle
@@ -183,7 +188,8 @@ See [Plugin Hooks](/architecture/hooks) for detailed hook documentation.
 
 ### 2. Worker Service
 Express.js HTTP server on port 37777 (configurable) with:
-- 8 HTTP/SSE endpoints for viewer UI
+- 10 search HTTP API endpoints (v5.4.0+)
+- 8 viewer UI HTTP/SSE endpoints
 - Async observation processing via Claude Agent SDK
 - Real-time updates via Server-Sent Events
 - Auto-managed by PM2 process manager
@@ -199,13 +205,19 @@ SQLite3 with better-sqlite3 driver featuring:
 
 See [Database Architecture](/architecture/database) for schema and FTS5 search.
 
-### 4. MCP Search Server (9 Tools)
-Provides 9 specialized search tools:
-- search_observations, search_sessions, search_user_prompts
-- find_by_concept, find_by_file, find_by_type
-- get_recent_context, get_context_timeline, get_timeline_by_query
+### 4. Search Skill (v5.4.0+)
+Skill-based search with progressive disclosure providing 10 search operations:
+- Search observations, sessions, prompts (full-text FTS5)
+- Filter by type, concept, file
+- Get recent context, timeline, timeline by query
+- API help documentation
 
-See [MCP Search Server](/architecture/mcp-search) for search tools and examples.
+**Token Savings**: ~2,250 tokens per session vs MCP approach
+- Skill frontmatter: ~250 tokens (loaded at session start)
+- Full instructions: ~2,500 tokens (loaded on-demand when invoked)
+- HTTP API endpoints instead of MCP tools
+
+See [Search Architecture](/architecture/search-architecture) for technical details and examples.
 
 ### 5. Viewer UI
 React + TypeScript web interface at http://localhost:37777 featuring: