feat(who): configurable scoring weights, MR refs, detail mode, and suffix path resolution

Expert mode now surfaces the specific MR references (project/path!iid) that
contributed to each expert's score, capped at 50 per user. A new --detail flag
adds per-MR breakdowns showing role (Author/Reviewer/both), note count, and
last activity timestamp.

Scoring weights (author_weight, reviewer_weight, note_bonus) are now
configurable via the config file's `scoring` section with validation that
rejects negative values. Defaults shift to author_weight=25, reviewer_weight=10,
note_bonus=1 — better reflecting that code authorship is a stronger expertise
signal than review assignment alone.

Path resolution gains suffix matching: typing "login.rs" auto-resolves to
"src/auth/login.rs" when unambiguous, with clear disambiguation errors when
multiple paths match. Project-scoping (-p) narrows the candidate set.

The MAX_MR_REFS_PER_USER constant is promoted to module scope for reuse
across expert and overlap modes. Human output shows MR refs inline and detail
sub-rows when requested. Robot JSON includes mr_refs, mr_refs_total,
mr_refs_truncated, and optional details array.

Includes comprehensive tests for suffix resolution, scoring weight
configurability, MR ref aggregation across projects, and detail mode.

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

src/cli/mod.rs

@@ -751,6 +751,13 @@ pub struct WhoArgs {
         help_heading = "Output"
     )]
     pub limit: u16,
+
+    /// Show per-MR detail breakdown (expert mode only)
+    #[arg(long, help_heading = "Output", overrides_with = "no_detail")]
+    pub detail: bool,
+
+    #[arg(long = "no-detail", hide = true, overrides_with = "detail")]
+    pub no_detail: bool,
 }
 
 #[derive(Parser)]