Add Calendar tools with CalDAV support (6 tools, 37 tests)

Tools: list_calendars, get_events, get_event, create_event, update_event, delete_event.
Uses icalendar v7.x for iCal parsing/generation. CalDAV REPORT queries for
reliable event lookup by UID and time-range filtering. ETag-based concurrency
on updates. Supports timed events, all-day events, and partial field updates.

Author: bigcat88

PROGRESS.md

@@ -33,14 +33,15 @@
 - [x] Collectives tools: list_collectives, get_collective_pages, get_collective_page (2026-03-29)
 - [x] App Management tools: list_apps, get_app_info, enable_app, disable_app (2026-03-30)
 - [x] User-permission integration tests: non-admin error handling validation (2026-03-30)
+- [x] Calendar tools: list_calendars, get_events, get_event, create_event, update_event, delete_event (2026-03-30)
 
 ### In Progress
 
 ### Blocked
 (none)
 
 ### Next Up
-- Phase 3 — Groupware (Calendar, Contacts, Tasks, Deck, Notes)
+- Phase 3 — Groupware (Contacts, Tasks, Deck, Notes)
 
 ## Phases
 
@@ -71,11 +72,12 @@
 | Mail | 5 | 29 |
 | Collectives | 3 | 22 |
 | App Management | 4 | 14 |
+| Calendar | 6 | 37 |
 | User Permissions | — | 15 |
 | Server | — | 7 |
 | Permissions | — | 34 |
 | Errors | — | 16 |
 | Client | — | 29 |
 | Config | — | 17 |
 | State | — | 2 |
-| **Total** | **67** | **542** |
+| **Total** | **73** | **579** |

pyproject.toml

@@ -22,6 +22,7 @@ classifiers = [
   "Programming Language :: Python :: 3.14",
 ]
 dependencies = [
+  "icalendar>=7",
   "mcp[cli]>=1.20",
   "niquests>=3",
 ]
@@ -107,7 +108,8 @@ venv = "venv"
 reportUnusedFunction = false
 reportPrivateUsage = false
 executionEnvironments = [
-  { root = "tests/test_client_retry.py", reportAttributeAccessIssue = false, reportUnknownMemberType = false }
+  { root = "tests/test_client_retry.py", reportAttributeAccessIssue = false, reportUnknownMemberType = false },
+  { root = "src/nc_mcp_server/tools/calendar.py", reportUnknownMemberType = false, reportUnknownVariableType = false, reportUnknownArgumentType = false },
 ]
 
 [tool.pytest]

src/nc_mcp_server/server.py

@@ -10,6 +10,7 @@
     activity,
     announcements,
     app_management,
+    calendar,
     collectives,
     comments,
     files,
@@ -53,6 +54,7 @@ def create_server(config: Config | None = None) -> FastMCP:
     activity.register(mcp)
     announcements.register(mcp)
     app_management.register(mcp)
+    calendar.register(mcp)
     collectives.register(mcp)
     comments.register(mcp)
     files.register(mcp)