Add ability to edit safe .env.example options to Settings

docs/roadmap_plan.md

@@ -44,6 +44,10 @@ Objective: improve research value with person-centric outputs.
 
 ## V6.2 - Access Control and Multi-User Readiness
 
+[ *More thoughts on user accounts:*
+* *Create a generic "view only" user that does not have the rights to alter any of the data*
+* *Limit user accounts access to data by Tag. I have distant family members that I would want to share the transcribed data with, but they would only be interested in a subset of it. For example my Cochran cousins would have no interest in Lancaster documents, so limit the Cochra Clan cousins to view-only access to documents tagged "cochran clan"* ]
+
 Objective: prepare for managed collaboration beyond single-user operation.
 
 ### Scope

docs/ui/pages/settings.md

@@ -2,35 +2,41 @@
 
 ## Purpose
 
-Settings manages installation-local registries and editable text assets from one route.
+Settings manages installation-local registries, safe runtime .env settings, and editable text assets from one route.
 
 ## Route
 
 | Route | Purpose |
 | --- | --- |
-| `/settings` | Manage Document Types, Person Roles, Tags, Prompts, and Home Page Text. |
+| `/settings` | Manage Runtime Settings, Document Types, Person Roles, Tags, Prompts, and Home Page Text. |
 
 ## Behavior
 
 - The page title is **Settings**.
 - Configuration surfaces are grouped as tabs:
+  - **Runtime Settings**
   - **Document Types**
   - **Person Roles**
   - **Tags**
   - **Prompts**
   - **Home Page Text**
+- Runtime Settings exposes an allowlisted set of non-secret fields synchronized with `Settings` model fields except excluded secret/unsafe fields.
+- Runtime Settings persists changes to `.env`, validates by constructing a `Settings` instance, and reports validation failures through the shared UI error presenter.
+- Runtime Settings changes require application restart to take effect.
 - Document Types, Person Roles, and Tags support Add/Edit/Delete with existing guardrails.
 - Prompts exposes only `transcribe_document.md` for editing and restore-from-backup.
 - Home Page Text edits the same Markdown content rendered on `/homepage`.
 
 ## Acceptance Checklist
 
-- `/ui/settings` renders all five tabs.
+- `/ui/settings` renders all six tabs.
 - Registry and prompt workflows keep existing validation and error handling.
+- Runtime Settings excludes secret fields and rejects invalid values.
 - Saving Home Page Text persists content for the homepage view.
 
 ## Implementation Anchors
 
 - `src/transcription/ui/pages/settings_page.py`
+- `src/transcription/ui/runtime_settings_store.py`
 - `src/transcription/ui/homepage_store.py`
 - `tests/ui/test_pages_registration.py`