feat: add codegraph clone command for copying indexes to worktrees

[Lint111]

Summary

• Adds a codegraph clone [target] CLI command that copies a CodeGraph index (codegraph.db) from one project/worktree to another
• Supports --source <path> for explicit source, --auto for git worktree parent auto-detection, and -f/--force to overwrite
• Only copies the db file (no WAL/SHM), creates the .codegraph/ directory and .gitignore in the target

Motivation

Git worktrees don't inherit the parent repo's .codegraph/ index. Dispatched CI/agent workers in fresh worktrees have no code intelligence until they run a full codegraph init (30–120s). This command copies the parent's db instantly (~186MB, sub-second), giving worktrees immediate code intelligence since the db uses relative paths.

Usage

# Explicit source
codegraph clone --source /path/to/main-repo

# Auto-detect from git worktree parent
codegraph clone --auto

# With explicit target and force overwrite
codegraph clone --auto /path/to/worktree --force

Test plan

• codegraph clone --source <initialized-repo> <empty-dir> copies the db and reports size
• codegraph clone --auto from a linked git worktree finds the main worktree's index
• Target with existing index skips without --force, overwrites with --force
• No source and no --auto prints usage error
• tsc --noEmit passes

🤖 Generated with Claude Code

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