refactor(graph): expose tracked-markdown path check for watcher (DIP)

[MarcoPorcellato]

Problem

LogseqGraphWatcher closure calls graph._resolved_path_is_tracked_markdown(path) — a private method on the entity/use-case boundary. External adapter code (watchdog handler) reaches through the abstraction.

Clean Architecture lens

Aspect	Assessment
Ring	Use Case (LogseqGraph + watcher adapter)
SOLID	DIP / ISP — watchers should depend on a narrow public protocol, not _-prefixed internals
Uncle Bob	Boundaries: keep framework details (watchdog) outside; graph exposes intent-revealing API

Proposed Solution

def is_tracked_markdown_path(self, path: Path) -> bool:
    """Return True if ``path`` is a pages/ or journals/ markdown file in this graph."""
    return self._resolved_path_is_tracked_markdown(path)

• Watcher uses public method only
• Unit test in tests/test_graph.py (watcher ignore vs accept paths)

Out of scope

• Rewriting watcher debounce logic

Definition of Done

• No private graph calls from LogseqGraphWatcher
• make all passes