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/search/fts.rs

@@ -1,16 +1,12 @@
 use crate::core::error::Result;
 use rusqlite::Connection;
 
-/// FTS query mode.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum FtsQueryMode {
-    /// Safe mode: each token wrapped in quotes, trailing * preserved on alphanumeric tokens.
     Safe,
-    /// Raw mode: query passed directly to FTS5 (for advanced users).
     Raw,
 }
 
-/// A single FTS5 search result.
 #[derive(Debug)]
 pub struct FtsResult {
     pub document_id: i64,
@@ -18,14 +14,6 @@ pub struct FtsResult {
     pub snippet: String,
 }
 
-/// Convert raw user input into a safe FTS5 query.
-///
-/// Safe mode:
-/// - Splits on whitespace
-/// - Wraps each token in double quotes (escaping internal quotes)
-/// - Preserves trailing `*` on alphanumeric-only tokens (prefix search)
-///
-/// Raw mode: passes through unchanged.
 pub fn to_fts_query(raw: &str, mode: FtsQueryMode) -> String {
     match mode {
         FtsQueryMode::Raw => raw.to_string(),
@@ -38,16 +26,13 @@ pub fn to_fts_query(raw: &str, mode: FtsQueryMode) -> String {
             let tokens: Vec<String> = trimmed
                 .split_whitespace()
                 .map(|token| {
-                    // Check if token ends with * and the rest is alphanumeric
                     if let Some(stem) = token.strip_suffix('*')
                         && !stem.is_empty()
                         && stem.chars().all(|c| c.is_alphanumeric() || c == '_')
                     {
-                        // Preserve prefix search: "stem"*
                         let escaped = stem.replace('"', "\"\"");
                         return format!("\"{}\"*", escaped);
                     }
-                    // Default: wrap in quotes, escape internal quotes
                     let escaped = token.replace('"', "\"\"");
                     format!("\"{}\"", escaped)
                 })
@@ -58,10 +43,6 @@ pub fn to_fts_query(raw: &str, mode: FtsQueryMode) -> String {
     }
 }
 
-/// Execute an FTS5 search query.
-///
-/// Returns results ranked by BM25 score (lower = better match) with
-/// contextual snippets highlighting matches.
 pub fn search_fts(
     conn: &Connection,
     query: &str,
@@ -97,14 +78,11 @@ pub fn search_fts(
     Ok(results)
 }
 
-/// Generate a fallback snippet for results without FTS snippets.
-/// Truncates at a word boundary and appends "...".
 pub fn generate_fallback_snippet(content_text: &str, max_chars: usize) -> String {
     if content_text.chars().count() <= max_chars {
         return content_text.to_string();
     }
 
-    // Collect the char boundary at max_chars to slice correctly for multi-byte content
     let byte_end = content_text
         .char_indices()
         .nth(max_chars)
@@ -112,7 +90,6 @@ pub fn generate_fallback_snippet(content_text: &str, max_chars: usize) -> String
         .unwrap_or(content_text.len());
     let truncated = &content_text[..byte_end];
 
-    // Walk backward to find a word boundary (space)
     if let Some(last_space) = truncated.rfind(' ') {
         format!("{}...", &truncated[..last_space])
     } else {
@@ -120,7 +97,6 @@ pub fn generate_fallback_snippet(content_text: &str, max_chars: usize) -> String
     }
 }
 
-/// Get the best snippet: prefer FTS snippet, fall back to truncated content.
 pub fn get_result_snippet(fts_snippet: Option<&str>, content_text: &str) -> String {
     match fts_snippet {
         Some(s) if !s.is_empty() => s.to_string(),
@@ -179,11 +155,9 @@ mod tests {
 
     #[test]
     fn test_prefix_only_alphanumeric() {
-        // Non-alphanumeric prefix: C++* should NOT be treated as prefix search
         let result = to_fts_query("C++*", FtsQueryMode::Safe);
         assert_eq!(result, "\"C++*\"");
 
-        // Pure alphanumeric prefix: auth* should be prefix search
         let result = to_fts_query("auth*", FtsQueryMode::Safe);
         assert_eq!(result, "\"auth\"*");
     }
@@ -205,7 +179,7 @@ mod tests {
         let content = "This is a moderately long piece of text that should be truncated at a word boundary for readability purposes";
         let result = generate_fallback_snippet(content, 50);
         assert!(result.ends_with("..."));
-        assert!(result.len() <= 55); // 50 + "..."
+        assert!(result.len() <= 55);
     }
 
     #[test]