v0.4.0

Breaking

• meta.json layout changed (corpus / walk / filters nesting). Re-run sift index build after upgrading; old stores are not migrated automatically.
• Daemon IPC types moved from sift_core::DaemonOp to sift_grep::index::daemon::{Daemon, DaemonOp, DaemonError}; core no longer exports daemon types.

Features

• Modular index daemon with async index update, --lazy build, and search-triggered background indexing
• MR-SW snapshot index store with unified reconcile and partial-path updates
• Walk unindexed corpus paths during daemon-enabled search for files not yet in the snapshot

Refactor

• Migrate grep/filter helpers to domain-type impls (PatternConfig::search_options, FilterConfig::candidate_config, OutputConfig::separators, ByteSize)
• Migrate core search helpers to domain types (CandidateFilter::collect, WalkOptions::discover_files, IgnoreConfig::matcher)
• Consolidate daemon into CLI-only index/daemon.rs (Daemon::send, Daemon::serve, Daemon::ensure_running); remove Serve, coordinator, and core IPC types
• Remove no-op DaemonOp::Watch IPC opcode; reload store metadata before daemon reconciles; fail serve on startup reconcile errors; rebind filesystem watcher when corpus root changes
• Unify TrigramIndex::build(config, dir, paths) API (empty paths = full corpus)

Documentation

• Add LICENSE-MIT, LICENSE-APACHE-2.0, CONTRIBUTING.md, SECURITY.md
• Add crate metadata and README release-scope section
• Expand rg compatibility matrix and integration test coverage