fix(ci): clear pre-existing mypy errors

The CI lane has been red across the last several commits with 5 mypy
errors that are unrelated to any of the recent feature work — fix them
all so the pipeline goes back to green.

Two cross-platform-tolerant patterns:

1. `# type: ignore[code, unused-ignore]`
   The `unused-ignore` code suppresses mypy's own "Unused type: ignore"
   meta-warning, which lets the same comment work on both Linux (where
   the underlying error fires and the ignore is needed) and macOS
   (where the symbol resolves correctly and the ignore would otherwise
   be flagged unused).

2. Apply the pattern to:
   - webdav_provider.py:431, 483 — st_birthtime is macOS-only; runtime
     code already handles the AttributeError, just needed
     [attr-defined, unused-ignore] to satisfy mypy on Linux.
   - webdav_server.py:25, 29 — waitress and cheroot have no
     library stubs in CI; needed [import-untyped, no-redef, unused-ignore].
   - cli.py:63 — same waitress story; [import-untyped, unused-ignore].

Verified:
  $ mypy --no-incremental cli.py services
  Success: no issues found in 8 source files

No behaviour change.  No new tests (the CI already runs pytest, this
just unsticks mypy so the rest of the lane can be observed).

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

Author: CrispStrobe

cli.py

@@ -60,7 +60,7 @@
     try:
         # Check for at least one server, matching webdav_server.py
         try:
-            import waitress  # type: ignore[import-untyped]  # noqa: F401  - dependency probe
+            import waitress  # type: ignore[import-untyped, unused-ignore]  # noqa: F401  - dependency probe
         except ImportError:
             import cheroot  # noqa: F401  - dependency probe
     except ImportError:

services/webdav_provider.py

@@ -428,7 +428,10 @@ def end_write(self, with_errors: bool):
                         modification_time = mtime.isoformat()
 
                         try:
-                            ctime = datetime.fromtimestamp(stat_info.st_birthtime, tz=timezone.utc)
+                            # st_birthtime is macOS/BSD-only; the AttributeError
+                            # branch covers Linux.  mypy's stat_result stub
+                            # doesn't expose it, so silence it here.
+                            ctime = datetime.fromtimestamp(stat_info.st_birthtime, tz=timezone.utc)  # type: ignore[attr-defined, unused-ignore]
                             creation_time = ctime.isoformat()
                         except AttributeError:
                             ctime = datetime.fromtimestamp(stat_info.st_ctime, tz=timezone.utc)
@@ -480,7 +483,8 @@ def end_write(self, with_errors: bool):
                             modification_time = mtime.isoformat()
 
                             try:
-                                ctime = datetime.fromtimestamp(stat_info.st_birthtime, tz=timezone.utc)
+                                # st_birthtime is macOS/BSD-only; AttributeError covers Linux.
+                                ctime = datetime.fromtimestamp(stat_info.st_birthtime, tz=timezone.utc)  # type: ignore[attr-defined, unused-ignore]
                                 creation_time = ctime.isoformat()
                             except AttributeError:
                                 ctime = datetime.fromtimestamp(stat_info.st_ctime, tz=timezone.utc)

services/webdav_server.py

@@ -22,11 +22,11 @@
 serve: Any = None
 wsgi: Any = None
 try:
-    from waitress import serve  # type: ignore[import-untyped, no-redef]  # noqa: F811
+    from waitress import serve  # type: ignore[import-untyped, no-redef, unused-ignore]  # noqa: F811
     WSGI_SERVER = 'waitress'
 except ImportError:
     try:
-        from cheroot import wsgi  # noqa: F811
+        from cheroot import wsgi  # type: ignore[import-untyped, no-redef, unused-ignore]  # noqa: F811
         WSGI_SERVER = 'cheroot'
     except ImportError:
         print("❌ No suitable WSGI server found. Install one of:")