refactor: convert f-string logging to lazy %-style format (G004)

Sweep all 1676 G004 violations across 112 files, converting
`logger.<level>(f"…{x}…")` to `logger.<level>("…%s…", x)`.

Why: ruff rule G004 was added to pyproject.toml to enforce lazy
%-style logging — defers formatting until the log level is enabled
and lets structured log tooling match the unformatted template.

Conversion preserves rendered output byte-for-byte:
- `{x}` → `%s` + `x`
- `{x!r}` / `{x!s}` / `{x!a}` → `%r` / `%s` / `%a`
- Format specs (`{x:.2f}`, `{x:>10}`) → `%s` + `format(x, 'spec')`
  (printf-style specs aren't 1:1 with Python format specs, so we
  delegate to `format()` to keep identical output)
- Literal `%` → `%%`
- Concatenated f-strings (`f"a {x} " "b"`) flattened
- Trailing kwargs (`exc_info=True`) preserved

Verified:
- `uv run ruff check --select G004` → 0 violations
- `uv run ty check -- nextcloud_mcp_server` → passes
- `uv run pytest tests/unit/` → 1010 passed

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

nextcloud_mcp_server/client/groups.py

@@ -67,7 +67,7 @@ class GroupsClient(BaseNextcloudClient):
             headers={"OCS-APIRequest": "true", "Accept": "application/json"},
         )
         response.raise_for_status()
-        logger.info(f"Created group: {groupid}")
+        logger.info("Created group: %s", groupid)
 
     @retry_on_429
     async def delete_group(self, groupid: str) -> None:
@@ -85,7 +85,7 @@ class GroupsClient(BaseNextcloudClient):
             headers={"OCS-APIRequest": "true", "Accept": "application/json"},
         )
         response.raise_for_status()
-        logger.info(f"Deleted group: {groupid}")
+        logger.info("Deleted group: %s", groupid)
 
     @retry_on_429
     async def get_group_members(self, groupid: str) -> List[str]:
@@ -150,4 +150,4 @@ class GroupsClient(BaseNextcloudClient):
             headers={"OCS-APIRequest": "true", "Accept": "application/json"},
         )
         response.raise_for_status()
-        logger.info(f"Updated group {groupid} displayname to: {displayname}")
+        logger.info("Updated group %s displayname to: %s", groupid, displayname)