feat: add read_text tool — extract text from PDF/TXT/MD (v0.4.0)

Adds read_text tool with pypdf integration for PDF text extraction,
plain-text decode for TXT/MD/CSV/JSON/etc, page-filter support,
max_chars truncation, and 11 mock-based tests.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "mcp-synology-filestation"
-version = "0.3.6"
+version = "0.4.0"
 description = "MCP server for Synology FileStation"
 requires-python = ">=3.12"
 dependencies = [
@@ -10,6 +10,7 @@ dependencies = [
     "keyring>=25.0.0",
     "click>=8.1.0",
     "rich>=13.0.0",
+    "pypdf>=4.0.0",
 ]
 
 [project.optional-dependencies]