feat: implement lore who — people intelligence commands (5 modes)

Add `lore who` command with 5 query modes answering collaboration questions
using existing DB data (280K notes, 210K discussions, 33K DiffNotes):

- Expert: who knows about a file/directory (DiffNote path analysis + MR breadth scoring)
- Workload: what is a person working on (assigned issues, authored/reviewing MRs, discussions)
- Active: what discussions need attention (unresolved resolvable, global/project-scoped)
- Overlap: who else is touching these files (dual author+reviewer role tracking)
- Reviews: what review patterns does a person have (prefix-based category extraction)

Includes migration 017 (5 composite indexes), CLI skeleton with clap conflicts_with
validation, robot JSON output with input+resolved_input reproducibility, human terminal
output, and 20 unit tests. All quality gates pass.

Closes: bd-1q8z, bd-34rr, bd-2rk9, bd-2ldg, bd-zqpf, bd-s3rc, bd-m7k1, bd-b51e,
bd-2711, bd-1rdi, bd-3mj2, bd-tfh3, bd-zibc, bd-g0d5

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

src/cli/mod.rs

@@ -193,6 +193,9 @@ pub enum Commands {
     /// Show a chronological timeline of events matching a query
     Timeline(TimelineArgs),
 
+    /// People intelligence: experts, workload, active discussions, overlap
+    Who(WhoArgs),
+
     #[command(hide = true)]
     List {
         #[arg(value_parser = ["issues", "mrs"])]
@@ -685,6 +688,56 @@ pub struct TimelineArgs {
     pub max_evidence: usize,
 }
 
+#[derive(Parser)]
+#[command(after_help = "\x1b[1mExamples:\x1b[0m
+  lore who src/features/auth/           # Who knows about this area?
+  lore who @asmith                      # What is asmith working on?
+  lore who @asmith --reviews            # What review patterns does asmith have?
+  lore who --active                     # What discussions need attention?
+  lore who --overlap src/features/auth/ # Who else is touching these files?
+  lore who --path README.md             # Expert lookup for a root file
+  lore who --path Makefile              # Expert lookup for a dotless root file")]
+pub struct WhoArgs {
+    /// Username or file path (path if contains /)
+    pub target: Option<String>,
+
+    /// Force expert mode for a file/directory path.
+    /// Root files (README.md, LICENSE, Makefile) are treated as exact matches.
+    /// Use a trailing `/` to force directory-prefix matching.
+    #[arg(long, help_heading = "Mode", conflicts_with_all = ["active", "overlap", "reviews"])]
+    pub path: Option<String>,
+
+    /// Show active unresolved discussions
+    #[arg(long, help_heading = "Mode", conflicts_with_all = ["target", "overlap", "reviews", "path"])]
+    pub active: bool,
+
+    /// Find users with MRs/notes touching this file path
+    #[arg(long, help_heading = "Mode", conflicts_with_all = ["target", "active", "reviews", "path"])]
+    pub overlap: Option<String>,
+
+    /// Show review pattern analysis (requires username target)
+    #[arg(long, help_heading = "Mode", requires = "target", conflicts_with_all = ["active", "overlap", "path"])]
+    pub reviews: bool,
+
+    /// Time window (7d, 2w, 6m, YYYY-MM-DD). Default varies by mode.
+    #[arg(long, help_heading = "Filters")]
+    pub since: Option<String>,
+
+    /// Scope to a project (supports fuzzy matching)
+    #[arg(short = 'p', long, help_heading = "Filters")]
+    pub project: Option<String>,
+
+    /// Maximum results per section (1..=500, bounded for output safety)
+    #[arg(
+        short = 'n',
+        long = "limit",
+        default_value = "20",
+        value_parser = clap::value_parser!(u16).range(1..=500),
+        help_heading = "Output"
+    )]
+    pub limit: u16,
+}
+
 #[derive(Parser)]
 pub struct CountArgs {
     /// Entity type to count (issues, mrs, discussions, notes, events)