feat: Complete Phase 5 - Instrument all 93 MCP tools

Applied @instrument_tool decorator to all 86 remaining tools
across 8 server files.

Instrumented files:
- calendar.py: 16 tools
- contacts.py: 7 tools
- deck.py: 25 tools
- webdav.py: 11 tools
- tables.py: 6 tools
- sharing.py: 5 tools
- cookbook.py: 13 tools
- semantic.py: 3 tools

Total: 93 tools instrumented (7 in notes.py + 86 in other files)

These metrics populate:
- MCP Tool Calls panel (by tool name and status)
- MCP Tool Duration panel (histogram)
- MCP Tool Errors panel (by tool name and error type)

This completes PR #295 - All 5 phases of metrics instrumentation done:
✅ Phase 1: Queue size metrics (2 locations)
✅ Phase 2: Health checks (1 location)
✅ Phase 3: Database operations (3 methods)
✅ Phase 4: OAuth token metrics (3 locations)
✅ Phase 5: MCP tool metrics (93 tools)

All 34 dashboard panels now have data sources.

nextcloud_mcp_server/server/webdav.py

@@ -5,6 +5,7 @@ from mcp.server.fastmcp import Context, FastMCP
 from nextcloud_mcp_server.auth import require_scopes
 from nextcloud_mcp_server.context import get_client
 from nextcloud_mcp_server.models import DirectoryListing, FileInfo, SearchFilesResponse
+from nextcloud_mcp_server.observability.metrics import instrument_tool
 from nextcloud_mcp_server.utils.document_parser import (
     is_parseable_document,
     parse_document,
@@ -17,6 +18,7 @@ def configure_webdav_tools(mcp: FastMCP):
     # WebDAV file system tools
     @mcp.tool()
     @require_scopes("files:read")
+    @instrument_tool
     async def nc_webdav_list_directory(
         ctx: Context, path: str = ""
     ) -> DirectoryListing:
@@ -50,6 +52,7 @@ def configure_webdav_tools(mcp: FastMCP):
 
     @mcp.tool()
     @require_scopes("files:read")
+    @instrument_tool
     async def nc_webdav_read_file(path: str, ctx: Context):
         """Read the content of a file from NextCloud.
 
@@ -130,6 +133,7 @@ def configure_webdav_tools(mcp: FastMCP):
 
     @mcp.tool()
     @require_scopes("files:write")
+    @instrument_tool
     async def nc_webdav_write_file(
         path: str, content: str, ctx: Context, content_type: str | None = None
     ):
@@ -158,6 +162,7 @@ def configure_webdav_tools(mcp: FastMCP):
 
     @mcp.tool()
     @require_scopes("files:write")
+    @instrument_tool
     async def nc_webdav_create_directory(path: str, ctx: Context):
         """Create a directory in NextCloud.
 
@@ -172,6 +177,7 @@ def configure_webdav_tools(mcp: FastMCP):
 
     @mcp.tool()
     @require_scopes("files:write")
+    @instrument_tool
     async def nc_webdav_delete_resource(path: str, ctx: Context):
         """Delete a file or directory in NextCloud.
 
@@ -186,6 +192,7 @@ def configure_webdav_tools(mcp: FastMCP):
 
     @mcp.tool()
     @require_scopes("files:write")
+    @instrument_tool
     async def nc_webdav_move_resource(
         source_path: str, destination_path: str, ctx: Context, overwrite: bool = False
     ):
@@ -206,6 +213,7 @@ def configure_webdav_tools(mcp: FastMCP):
 
     @mcp.tool()
     @require_scopes("files:write")
+    @instrument_tool
     async def nc_webdav_copy_resource(
         source_path: str, destination_path: str, ctx: Context, overwrite: bool = False
     ):
@@ -226,6 +234,7 @@ def configure_webdav_tools(mcp: FastMCP):
 
     @mcp.tool()
     @require_scopes("files:read")
+    @instrument_tool
     async def nc_webdav_search_files(
         ctx: Context,
         scope: str = "",
@@ -342,6 +351,7 @@ def configure_webdav_tools(mcp: FastMCP):
 
     @mcp.tool()
     @require_scopes("files:read")
+    @instrument_tool
     async def nc_webdav_find_by_name(
         pattern: str, ctx: Context, scope: str = "", limit: int | None = None
     ) -> SearchFilesResponse:
@@ -369,6 +379,7 @@ def configure_webdav_tools(mcp: FastMCP):
 
     @mcp.tool()
     @require_scopes("files:read")
+    @instrument_tool
     async def nc_webdav_find_by_type(
         mime_type: str, ctx: Context, scope: str = "", limit: int | None = None
     ) -> SearchFilesResponse:
@@ -396,6 +407,7 @@ def configure_webdav_tools(mcp: FastMCP):
 
     @mcp.tool()
     @require_scopes("files:read")
+    @instrument_tool
     async def nc_webdav_list_favorites(
         ctx: Context, scope: str = "", limit: int | None = None
     ) -> SearchFilesResponse: