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/document_processors/pymupdf.py

@@ -59,7 +59,8 @@ class PyMuPDFProcessor(DocumentProcessor):
         if self.extract_images:
             self.image_dir.mkdir(exist_ok=True, parents=True)
             logger.info(
-                f"Initialized PyMuPDFProcessor with image extraction to {self.image_dir}"
+                "Initialized PyMuPDFProcessor with image extraction to %s",
+                self.image_dir,
             )
         else:
             logger.info("Initialized PyMuPDFProcessor without image extraction")
@@ -175,9 +176,11 @@ class PyMuPDFProcessor(DocumentProcessor):
                 await progress_callback(100, 100, "Processing complete")
 
             logger.info(
-                f"Successfully processed PDF {filename or '<bytes>'}: "
-                f"{metadata['page_count']} pages, {len(md_text)} chars, "
-                f"{metadata.get('image_count', 0)} images"
+                "Successfully processed PDF %s: %s pages, %s chars, %s images",
+                filename or "<bytes>",
+                metadata["page_count"],
+                len(md_text),
+                metadata.get("image_count", 0),
             )
 
             return ProcessingResult(
@@ -250,5 +253,5 @@ class PyMuPDFProcessor(DocumentProcessor):
             test_doc.close()
             return True
         except Exception as e:
-            logger.error(f"PyMuPDF health check failed: {e}")
+            logger.error("PyMuPDF health check failed: %s", e)
             return False