Auto-label gestures from recordings and generalize plugin list expansion in binding picker

[multiplex55]

Motivation

• Improve UX when applying a new recording by auto-naming gestures from recorded tokens while keeping manually-set names intact.
• Simplify and generalize the action-picker list expansion so list-backed plugins (clipboard, folders, bookmarks, emoji, notes, etc.) are queried uniformly instead of special-casing folders/bookmarks.
• Make the label-generation rule deterministic and testable via a helper so unit tests can validate rename behavior.

Description

• Added deterministic label helpers: is_default_generated_label, normalize_recorded_tokens_for_label, and label_from_recorded_tokens to sanitize, truncate, and format auto-generated labels as Gesture <TOKENS>.
• Centralized recording application into MgGesturesDialog::apply_recording_to_entry so both the Use Recording button and drag-completion path set tokens, stroke, token_buffer consistently and auto-update the label only when is_default_generated_label returns true.
• Replaced ad-hoc folder/bookmark logic with a plugin-to-query-prefix mapping via list_query_prefix_for_plugin and a resolver resolve_action_source that calls plugin.search(<list-prefix + filter>) for mapped plugins and falls back to plugin.commands() when needed.
• Factored picked-action handling into apply_action_pick and append_query_args to reliably set BindingKind, action, and args for query:-prefixed actions, launcher:toggle, and regular execute actions, including safe concatenation of extra args.
• Updated binding dialog UI to use resolve_action_source and apply_action_pick so selected list entries write correct BindingKind, action, and args fields.
• Added unit tests in mod tests covering auto_label_is_applied_only_for_default_generated_labels, customized_label_is_preserved_when_new_recording_is_applied, and resolve_action_source_prefers_mapped_list_search_and_falls_back_to_commands.

Testing

• Ran cargo fmt successfully to format changes.
• Attempted cargo test mouse_gestures_dialog -- --nocapture, but tests could not run in this environment due to the workspace resolving dependencies that require rustc 1.88.0 while the available toolchain is rustc 1.87.0; tests were added but not executed here because of that toolchain mismatch.

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Codex Task