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>

tests/load/oauth_workloads.py

@@ -115,7 +115,7 @@ class Workflow(ABC):
             return step_result
         except Exception as e:
             duration = time.time() - start
-            logger.error(f"Step {step_name} failed for user {user.username}: {e}")
+            logger.error("Step %s failed for user %s: %s", step_name, user.username, e)
             step_result = WorkflowStepResult(
                 step_name=step_name,
                 user=user.username,
@@ -236,7 +236,7 @@ class NoteShareWorkflow(Workflow):
             return self._finish(success=True)
 
         except Exception as e:
-            logger.error(f"Note share workflow failed: {e}")
+            logger.error("Note share workflow failed: %s", e)
             return self._finish(False, error=str(e))
 
 
@@ -338,7 +338,7 @@ class CollaborativeEditWorkflow(Workflow):
             return self._finish(success=True)
 
         except Exception as e:
-            logger.error(f"Collaborative edit workflow failed: {e}")
+            logger.error("Collaborative edit workflow failed: %s", e)
             return self._finish(False, error=str(e))
 
 
@@ -424,7 +424,7 @@ class FileShareAndDownloadWorkflow(Workflow):
             return self._finish(success=True)
 
         except Exception as e:
-            logger.error(f"File share workflow failed: {e}")
+            logger.error("File share workflow failed: %s", e)
             return self._finish(False, error=str(e))