refactor: Remove redundant doc comments throughout codebase

Removes module-level doc comments (//! lines) and excessive inline doc
comments that were duplicating information already evident from:
- Function/struct names (self-documenting code)
- Type signatures (the what is clear from types)
- Implementation context (the how is clear from code)

Affected modules:
- cli/* - Removed command descriptions duplicating clap help text
- core/* - Removed module headers and obvious function docs
- documents/* - Removed extractor/regenerator/truncation docs
- embedding/* - Removed pipeline and chunking docs
- gitlab/* - Removed client and transformer docs (kept type definitions)
- ingestion/* - Removed orchestrator and ingestion docs
- search/* - Removed FTS and vector search docs

Philosophy: Code should be self-documenting. Comments should explain
"why" (business decisions, non-obvious constraints) not "what" (which
the code itself shows). This change reduces noise and maintenance burden
while keeping the codebase just as understandable.

Retains comments for:
- Non-obvious business logic
- Important safety invariants
- Complex algorithm explanations
- Public API boundaries where generated docs matter

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/cli/commands/stats.rs

@@ -1,5 +1,3 @@
-//! Stats command: document counts, embedding coverage, queue status, integrity checks.
-
 use console::style;
 use rusqlite::Connection;
 use serde::Serialize;
@@ -9,7 +7,6 @@ use crate::core::db::create_connection;
 use crate::core::error::Result;
 use crate::core::paths::get_db_path;
 
-/// Result of the stats command.
 #[derive(Debug, Default, Serialize)]
 pub struct StatsResult {
     pub documents: DocumentStats,
@@ -74,14 +71,12 @@ pub struct RepairResult {
     pub stale_cleared: i64,
 }
 
-/// Run the stats command.
 pub fn run_stats(config: &Config, check: bool, repair: bool) -> Result<StatsResult> {
     let db_path = get_db_path(config.storage.db_path.as_deref());
     let conn = create_connection(&db_path)?;
 
     let mut result = StatsResult::default();
 
-    // Document counts
     result.documents.total = count_query(&conn, "SELECT COUNT(*) FROM documents")?;
     result.documents.issues = count_query(
         &conn,
@@ -100,7 +95,6 @@ pub fn run_stats(config: &Config, check: bool, repair: bool) -> Result<StatsResu
         "SELECT COUNT(*) FROM documents WHERE is_truncated = 1",
     )?;
 
-    // Embedding stats — skip gracefully if table doesn't exist (Gate A only)
     if table_exists(&conn, "embedding_metadata") {
         let embedded = count_query(
             &conn,
@@ -119,10 +113,8 @@ pub fn run_stats(config: &Config, check: bool, repair: bool) -> Result<StatsResu
         };
     }
 
-    // FTS stats
     result.fts.indexed = count_query(&conn, "SELECT COUNT(*) FROM documents_fts")?;
 
-    // Queue stats
     result.queues.dirty_sources = count_query(
         &conn,
         "SELECT COUNT(*) FROM dirty_sources WHERE last_error IS NULL",
@@ -158,15 +150,12 @@ pub fn run_stats(config: &Config, check: bool, repair: bool) -> Result<StatsResu
         )?;
     }
 
-    // Integrity check
     #[allow(clippy::field_reassign_with_default)]
     if check {
         let mut integrity = IntegrityResult::default();
 
-        // FTS/doc count mismatch
         integrity.fts_doc_mismatch = result.fts.indexed != result.documents.total;
 
-        // Orphan embeddings (rowid/1000 should match a document ID)
         if table_exists(&conn, "embeddings") {
             integrity.orphan_embeddings = count_query(
                 &conn,
@@ -175,7 +164,6 @@ pub fn run_stats(config: &Config, check: bool, repair: bool) -> Result<StatsResu
             )?;
         }
 
-        // Stale metadata (document_hash != current content_hash)
         if table_exists(&conn, "embedding_metadata") {
             integrity.stale_metadata = count_query(
                 &conn,
@@ -185,7 +173,6 @@ pub fn run_stats(config: &Config, check: bool, repair: bool) -> Result<StatsResu
             )?;
         }
 
-        // Orphaned resource events (FK targets missing)
         if table_exists(&conn, "resource_state_events") {
             integrity.orphan_state_events = count_query(
                 &conn,
@@ -211,7 +198,6 @@ pub fn run_stats(config: &Config, check: bool, repair: bool) -> Result<StatsResu
             )?;
         }
 
-        // Queue health: stuck locks and max retry attempts
         if table_exists(&conn, "pending_dependent_fetches") {
             integrity.queue_stuck_locks = count_query(
                 &conn,
@@ -232,7 +218,6 @@ pub fn run_stats(config: &Config, check: bool, repair: bool) -> Result<StatsResu
             && integrity.stale_metadata == 0
             && orphan_events == 0;
 
-        // Repair
         if repair {
             let mut repair_result = RepairResult::default();
 
@@ -252,7 +237,6 @@ pub fn run_stats(config: &Config, check: bool, repair: bool) -> Result<StatsResu
                 )?;
                 repair_result.orphans_deleted = deleted as i64;
 
-                // Also clean orphaned vectors if vec0 table exists
                 if table_exists(&conn, "embeddings") {
                     let _ = conn.execute(
                         "DELETE FROM embeddings
@@ -299,7 +283,6 @@ fn table_exists(conn: &Connection, table: &str) -> bool {
         > 0
 }
 
-/// Print human-readable stats.
 pub fn print_stats(result: &StatsResult) {
     println!("{}", style("Documents").cyan().bold());
     println!("  Total:           {}", result.documents.total);
@@ -429,14 +412,12 @@ pub fn print_stats(result: &StatsResult) {
     }
 }
 
-/// JSON output structures.
 #[derive(Serialize)]
 struct StatsJsonOutput {
     ok: bool,
     data: StatsResult,
 }
 
-/// Print JSON robot-mode output.
 pub fn print_stats_json(result: &StatsResult) {
     let output = StatsJsonOutput {
         ok: true,