feat: rename worktree hooks with deprecation support

[avihut]

Summary

• Rename 4 worktree-scoped hooks with a worktree- prefix (pre-create → worktree-pre-create, etc.) for clarity
• Old hook filenames remain functional with deprecation warnings until v2.0.0
• Add git daft hooks migrate command to automatically rename deprecated hook files
• git daft hooks status now detects and warns about deprecated hook names
• Config keys fall back to deprecated keys for backwards compatibility

Fixes #84

Details

Current	New	Scope
post-clone	post-clone (unchanged)	repo
post-init	post-init (unchanged)	repo
pre-create	worktree-pre-create	worktree
post-create	worktree-post-create	worktree
pre-remove	worktree-pre-remove	worktree
post-remove	worktree-post-remove	worktree

Deprecation behavior:

• Before v2.0.0: Old filenames are discovered, executed, and a deprecation warning is emitted
• v2.0.0+: Controlled by flipping EXECUTE_DEPRECATED_HOOKS from true to false

Migration command:

git daft hooks migrate [--dry-run]

Scans all worktree .daft/hooks/ directories and ~/.config/daft/hooks/, renames deprecated files, handles conflicts when both old and new names exist.

Test plan

• All 140 unit tests pass (cargo test)
• cargo clippy -- -D warnings passes clean
• cargo fmt -- --check passes clean
• New unit tests for deprecated_filename(), from_filename(), deprecated_config_key()
• New unit tests for deprecated hook discovery and both-names-exist conflict
• New integration tests: deprecated hook warning, migrate basic, migrate dry-run, migrate conflict
• CI integration tests pass on Linux and macOS
• Manual testing: create hook with old name, verify warning, run migrate, verify clean status

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