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/integration/sampling_support.py

@@ -62,7 +62,7 @@ def create_sampling_callback(provider: Provider):
         params: types.CreateMessageRequestParams,
     ) -> types.CreateMessageResult | types.ErrorData:
         """Handle sampling requests using the configured provider."""
-        logger.debug(f"Sampling callback invoked with {len(params.messages)} messages")
+        logger.debug("Sampling callback invoked with %s messages", len(params.messages))
 
         # Extract messages and build prompt
         messages_text = []
@@ -77,7 +77,7 @@ def create_sampling_callback(provider: Provider):
         if params.systemPrompt:
             prompt = f"System: {params.systemPrompt}\n\n{prompt}"
 
-        logger.debug(f"Generating response for prompt ({len(prompt)} chars)")
+        logger.debug("Generating response for prompt (%s chars)", len(prompt))
 
         try:
             # Generate response using provider
@@ -87,7 +87,9 @@ def create_sampling_callback(provider: Provider):
                 max_tokens=params.maxTokens,
             )
 
-            logger.info(f"Sampling completed: {len(response)} chars from {model_name}")
+            logger.info(
+                "Sampling completed: %s chars from %s", len(response), model_name
+            )
 
             return types.CreateMessageResult(
                 role="assistant",
@@ -96,7 +98,7 @@ def create_sampling_callback(provider: Provider):
                 stopReason="endTurn",
             )
         except Exception as e:
-            logger.error(f"Generation failed ({provider.__class__.__name__}): {e}")
+            logger.error("Generation failed (%s): %s", provider.__class__.__name__, e)
             return types.ErrorData(
                 code=types.INTERNAL_ERROR,
                 message=f"Generation failed: {e!s}",