Add exact-match integration tests for note searches

[multiplex55]

Motivation

• Ensure LauncherApp::search() honors settings.match_exact = true for note-related commands and returns resolved note actions rather than only query:* suggestions.
• Verify note today, note search <term>, and a transformed command path (note new Hello World) behave deterministically under exact-match mode.

Description

• Import note helpers and add setup_notes_env to seed ML_NOTES_DIR/HOME and call save_notes() for deterministic note test setup.
• Add an integration test note_today_returns_resolved_note_action_when_exact_match_enabled that asserts note today yields at least one result whose action starts with note:new: and not only query:* when match_exact is enabled.
• Add an integration test note_search_matches_note_content_when_exact_match_enabled that seeds notes (one containing needle) and asserts note search needle returns note:open:beta and not only query:* when match_exact is enabled.
• Add an integration test note_new_generates_slugged_action_when_exact_match_enabled that asserts note new Hello World produces note:new:hello-world and not query:* under exact-match mode.
• Reuse existing tempdir and set_current_dir patterns and LauncherApp::new(...) scaffolding used elsewhere in tests for consistency.

Testing

• Executed cargo test --test plugin_exact_match to run the new tests, but the build failed due to a missing system dependency required by a transitive crate (alsa-sys), specifically the system alsa pkg-config metadata/library; no test assertions were executed to completion in this environment.

---

Codex Task