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/utils/document_parser.py

@@ -72,7 +72,7 @@ async def parse_document(
 
     registry = get_registry()
 
-    logger.debug(f"Parsing document of type '{content_type}'")
+    logger.debug("Parsing document of type '%s'", content_type)
 
     try:
         # Process using registry (auto-selects processor based on MIME type)
@@ -83,12 +83,14 @@ async def parse_document(
             progress_callback=progress_callback,
         )
 
-        logger.info(f"Successfully parsed document with '{result.processor}' processor")
+        logger.info(
+            "Successfully parsed document with '%s' processor", result.processor
+        )
 
         return result.text, result.metadata
 
     except ProcessorError as e:
-        logger.error(f"Document processing failed: {e}")
+        logger.error("Document processing failed: %s", e)
         # Fallback to base64 with error metadata
         parsed_text = f"Document could not be parsed. Base64 content: {base64.b64encode(content).decode('ascii')[:200]}..."
         metadata = {