bug: SQLite queue sequence not reset with --clean flag

## Problem

When using the `--clean` flag to do a full reindex, the SQLite autoincrement sequence is not reset. This causes document IDs to continue from the previous run rather than starting from 1.

## Impact

- **Functional**: None - the indexer works correctly
- **Observability**: Makes progress tracking via ID ranges confusing/misleading
- **Example**: After a previous run indexed 5M docs, a new `--clean` run starts IDs at 5,000,001 instead of 1

## Root Cause

The `clear()` method in `src/utils/sqlite_queue.ts` only deletes rows but doesn't reset the sequence:

```typescript
async clear(): Promise {
this.logger.info('Clearing queue (removing all items including failed)');
const result = this.db.prepare('DELETE FROM queue').run();
this.logger.info(`Cleared ${result.changes} items from queue`);

// Also clear the enqueue_completed flag
this.db.prepare("DELETE FROM queue_metadata WHERE key = 'enqueue_completed'").run();

// MISSING: Reset sqlite_sequence
}
```

SQLite behavior:
- `DELETE FROM table` removes all rows but preserves the AUTOINCREMENT sequence
- The sequence is stored in `sqlite_sequence` table

## Fix

Add one line to reset the sequence:

```typescript
async clear(): Promise {
this.logger.info('Clearing queue (removing all items including failed)');
const result = this.db.prepare('DELETE FROM queue').run();
this.logger.info(`Cleared ${result.changes} items from queue`);

// Reset autoincrement sequence so IDs start from 1 again
this.db.prepare("DELETE FROM sqlite_sequence WHERE name = 'queue'").run();

// Also clear the enqueue_completed flag
this.db.prepare("DELETE FROM queue_metadata WHERE key = 'enqueue_completed'").run();
}
```

## Severity

Low - cosmetic/observability issue only, not a functional bug.

Start in src/utils/sqlite_queue.ts and inspect the clear() method and its existing queue cleanup statements. Verify the SQLite queue schema and run the project's available checks, then confirm that using --clean removes the prior sequence state so the next indexed document receives ID 1.

Written by the indexing model from the issue text.