Add distributed settings and workspace import/export (M5)

docs/spec/07-settings.md

@@ -1,13 +1,15 @@
 # 07 · Settings
 
-Astrolabe provides a **Settings** modal where users tune appearance, the spec editor, preview performance, and date formatting. All settings persist locally and apply across sessions on the same device. Settings load at startup; any unknown or missing value falls back to its factory default, so older or partial saved settings never break the app.
+Astrolabe lets users tune appearance, the spec editor, preview performance, and date formatting. Rather than a separate Settings modal, **each preference lives next to what it affects and applies immediately** — the appearance theme is a header toggle, editor preferences sit in the editor pane, render performance in the preview pane, and date formatting in the library. All settings persist locally and apply across sessions on the same device. Settings load at startup; any unknown or missing value falls back to its factory default, so older or partial saved settings never break the app.
 
-## Opening the modal
+> **Why distributed, not a modal (resolved).** Settings were originally specified as one central modal with an explicit Apply/Cancel commit. A design review (see _Architecture 10 · Interaction & Feedback_) moved them to per-pane, live-applied controls: it matches how theme and preview fit mode already work, lets a change’s effect be seen in the very pane being configured, and keeps each settings block independently extensible. The settings, options, and defaults below are unchanged — only their presentation and commit model changed.
 
-- An entry in the application header opens the Settings modal.
-- The keyboard shortcut **Cmd/Ctrl+,** also opens it.
-- The modal is grouped into clearly titled sections: Appearance, Editor, Performance, and Formatting.
-- The modal can be dismissed with a Cancel action or the standard modal-close affordance; dismissing without applying discards any pending edits and restores the last saved values.
+## Opening the settings
+
+- **Appearance (UI theme)** is a one-click toggle in the application header.
+- **Editor**, **Performance**, and **Formatting** clusters are each opened by a small **settings (gear) control** in the toolbar of the pane they govern — the editor pane, the preview pane, and the library, respectively. The control discloses a popover of that cluster’s controls.
+- The keyboard shortcut **Cmd/Ctrl+,** opens the **Editor** settings cluster (the primary configuration surface).
+- A disclosed popover is dismissed with **Esc** (which returns focus to its gear) or by clicking outside it; at most one settings popover is open at a time.
 
 ## Settings
 
@@ -19,9 +21,9 @@ Controls the overall UI theme. Choosing the Dark theme switches the whole applic
 | -------- | ----------- | ------- |
 | UI theme | Light, Dark | Light   |
 
-The UI theme is also exposed as a **header toggle** for one-click switching; it
-reads and writes the same persisted `ui.theme` value as this Appearance control,
-so the two always agree. (The toggle shipped in M1.5, ahead of this modal.)
+The UI theme is a one-click **header toggle** (shipped in M1.5). It reads and
+writes the persisted `ui.theme` value directly and applies immediately — there is
+no separate Appearance control to keep in sync.
 
 ### Editor
 
@@ -69,15 +71,14 @@ Governs how dates are rendered throughout the app, for example the timestamps sh
 
 ## Related persisted preferences (documented elsewhere)
 
-The following preferences also persist locally across sessions but are managed outside this modal and are documented in their own sections:
+The following preferences also persist locally across sessions and, like the clusters above, are managed by controls in the pane they affect; they are documented in their own sections:
 
 - **Preview fit mode** — how the preview is sized/fit; see _Live Preview_.
 - **Snippet sort preference** — the snippet list's sort field and direction; see _Snippet Library_.
 
 ## Behaviors
 
-- **Apply / save**: An explicit Apply action writes all changes; they take effect immediately (e.g. the UI theme switches at once).
-- **Dirty indication**: While the form differs from the last saved state, the modal shows an "Unsaved changes" indicator.
-- **Cancel / dismiss**: Closing without applying reverts the form to the last saved values and leaves stored settings untouched.
-- **Reset to defaults**: A Reset action restores every setting to its factory default. It requires explicit confirmation before applying, then saves the defaults.
-- **Startup load**: Settings are read on startup and applied to the UI and editor; missing or unrecognized values silently use their defaults.
+- **Live apply**: Every control applies its change immediately — there is no Apply/Cancel commit step. The effect is visible in the pane being configured (the editor reflows, the preview re-renders at the new debounce, the library re-formats its dates), so no separate confirmation is needed. This matches the always-live header theme toggle and preview Fit control.
+- **Reset to defaults**: The **Editor** cluster offers a Reset that restores the editor settings to their factory defaults. (Other clusters are single, self-evident controls; there is no global "reset everything" — each control is individually reversible.)
+- **No dirty / discard state**: Because changes commit as made, there is no "unsaved changes" indicator and nothing to discard on dismiss; closing a settings popover simply hides it.
+- **Startup load**: Settings are read on startup and applied to the UI, editor, preview, and library; missing or unrecognized values silently use their defaults.