refactor(core): extract path_resolver module, fix old_path matching in who

Extract shared path resolution logic from who.rs into a new
core::path_resolver module for cross-module reuse. Functions moved:
escape_like, normalize_repo_path, PathQuery, SuffixResult,
build_path_query, suffix_probe. Duplicate escape_like copies removed
from list.rs, project.rs, and filters.rs — all now import from
path_resolver.

Additionally fixes two bugs in query_expert_details() and
query_overlap() where only position_new_path was checked (missing
old_path matches for renamed files) and state filter excluded 'closed'
MRs despite the main scoring query including them with a decay
multiplier.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/core/mod.rs

@@ -9,6 +9,7 @@ pub mod lock;
 pub mod logging;
 pub mod metrics;
 pub mod note_parser;
+pub mod path_resolver;
 pub mod paths;
 pub mod payloads;
 pub mod project;