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/core/payloads.rs

@@ -1,5 +1,3 @@
-//! Raw payload storage with optional compression and deduplication.
-
 use flate2::Compression;
 use flate2::read::GzDecoder;
 use flate2::write::GzEncoder;
@@ -10,26 +8,21 @@ use std::io::{Read, Write};
 use super::error::Result;
 use super::time::now_ms;
 
-/// Options for storing a payload.
 pub struct StorePayloadOptions<'a> {
     pub project_id: Option<i64>,
-    pub resource_type: &'a str, // 'project' | 'issue' | 'mr' | 'note' | 'discussion'
-    pub gitlab_id: &'a str,     // TEXT because discussion IDs are strings
+    pub resource_type: &'a str,
+    pub gitlab_id: &'a str,
     pub json_bytes: &'a [u8],
     pub compress: bool,
 }
 
-/// Store a raw API payload with optional compression and deduplication.
-/// Returns the row ID (either new or existing if duplicate).
 pub fn store_payload(conn: &Connection, options: StorePayloadOptions) -> Result<i64> {
     let json_bytes = options.json_bytes;
 
-    // 2. SHA-256 hash the JSON bytes (pre-compression)
     let mut hasher = Sha256::new();
     hasher.update(json_bytes);
     let payload_hash = format!("{:x}", hasher.finalize());
 
-    // 3. Check for duplicate by (project_id, resource_type, gitlab_id, payload_hash)
     let existing: Option<i64> = conn
         .query_row(
             "SELECT id FROM raw_payloads
@@ -44,12 +37,10 @@ pub fn store_payload(conn: &Connection, options: StorePayloadOptions) -> Result<
         )
         .ok();
 
-    // 4. If duplicate, return existing ID
     if let Some(id) = existing {
         return Ok(id);
     }
 
-    // 5. Compress if requested
     let (encoding, payload_bytes): (&str, std::borrow::Cow<'_, [u8]>) = if options.compress {
         let mut encoder = GzEncoder::new(Vec::new(), Compression::default());
         encoder.write_all(json_bytes)?;
@@ -58,7 +49,6 @@ pub fn store_payload(conn: &Connection, options: StorePayloadOptions) -> Result<
         ("identity", std::borrow::Cow::Borrowed(json_bytes))
     };
 
-    // 6. INSERT with content_encoding
     conn.execute(
         "INSERT INTO raw_payloads
          (source, project_id, resource_type, gitlab_id, fetched_at, content_encoding, payload_hash, payload)
@@ -77,8 +67,6 @@ pub fn store_payload(conn: &Connection, options: StorePayloadOptions) -> Result<
     Ok(conn.last_insert_rowid())
 }
 
-/// Read a raw payload by ID, decompressing if necessary.
-/// Returns None if not found.
 pub fn read_payload(conn: &Connection, id: i64) -> Result<Option<serde_json::Value>> {
     let row: Option<(String, Vec<u8>)> = conn
         .query_row(
@@ -92,7 +80,6 @@ pub fn read_payload(conn: &Connection, id: i64) -> Result<Option<serde_json::Val
         return Ok(None);
     };
 
-    // Decompress if needed
     let json_bytes = if encoding == "gzip" {
         let mut decoder = GzDecoder::new(&payload_bytes[..]);
         let mut decompressed = Vec::new();
@@ -117,7 +104,6 @@ mod tests {
         let db_path = dir.path().join("test.db");
         let conn = create_connection(&db_path).unwrap();
 
-        // Create minimal schema for testing
         conn.execute_batch(
             "CREATE TABLE raw_payloads (
                 id INTEGER PRIMARY KEY,
@@ -212,6 +198,6 @@ mod tests {
         )
         .unwrap();
 
-        assert_eq!(id1, id2); // Same payload returns same ID
+        assert_eq!(id1, id2);
     }
 }