fix: FilesTab empty state, button styles, text preview, menu positioning

- Add reactive $: block in FilesTab to auto-load files on selectedNode change
- Copy .btn/.btn-primary/.btn-sm styles into NotesTab.svelte and FilesTab.svelte (scoped CSS)
- Fix FilePreviewModal: render .md with MarkdownPreview, text files in <pre><code>, external open in footer
- Expand codeNames/textMimes in fileUtils.js to cover all text file types
- Add fallback text read for unknown file types in _openPreview
- Fix toggleMenu in FileTreeRow: position menu near button using getBoundingClientRect
- Add debug logs for file open flow and menu positioning
- Add tabindex+keydown to MarkdownPreview div (a11y partial fix)

Co-Authored-By: OWL (Hermes Agent) <hermes@nousresearch.com>

docs/frontend-architecture.md

@@ -4,7 +4,7 @@
 
 - **Framework**: Svelte 4 (runes-free, compiler-only)
 - **Build tool**: Vite 5
-- **GUI shell**: Wails v2 (Go backend + WebKit frontend)
+- **GUI shell**: Wails v2 (Go backend + WebKit GTK frontend)
 - **Language**: Plain JavaScript (no TypeScript in Svelte files — `lang="ts"` is NOT used)
 
 ## Source Structure
@@ -37,7 +37,11 @@ frontend/src/
     markdown/                    # Markdown rendering + internal links
     util/                        # Keyboard layout helper
     components/
+      OverviewTab.svelte         # Overview tab: meta, quick actions, recent items
+      files/
+        FilesTab.svelte          # Files tab: file browser, preview, import, rename
       notes/
+        NotesTab.svelte          # Notes tab: note list, create form
         MarkdownEditor.svelte    # Markdown textarea with toolbar
         MarkdownPreview.svelte   # Rendered markdown preview
         NoteEditorPanel.svelte   # Editor + preview layout, public API: insertText()
@@ -51,13 +55,59 @@ frontend/src/
 
 1. **Global UI state**: sidebar (system views, workspace tree), active tab, selected node/section
 2. **Lifecycle**: startup checks (GetStartupStatus, VerstakVersion, ListWorkspaceTree), event listeners
-3. **Top-level modals**: confirm, rename, import, worklog, inbox assign, link edit, settings, file preview
+3. **Top-level modals**: confirm, node rename, import (removed — now in FilesTab), worklog, inbox assign, link edit, settings, trash preview
 4. **Cross-cutting concerns**: navigation history (goBack, rememberNavigation), keyboard shortcuts, drag-and-drop orchestration, capture/inbox flow
+5. **Note editor lifecycle**: `noteEditor` state, `doOpenNote()`, `saveCurrentNote()`, `closeNoteEditor()`, link modal, internal link picker
 
 App.svelte is **NOT** responsible for:
-- Individual tab content (Overview, Notes, Files) — these are inlined but should be extracted
-- Note editor internals — `NoteEditorPanel.svelte` + `MarkdownEditor.svelte` handle this
-- Settings sections — each has its own `Settings*.svelte`
+- **Files tab** → `FilesTab.svelte` (owns all file browser state, preview, import, rename)
+- **Notes tab list** → `NotesTab.svelte` (owns note list UI, create form; editor stays in App)
+- **Overview tab** → `OverviewTab.svelte` (pure display: meta, quick actions, recent items)
+- **Settings sections** → each has its own `Settings*.svelte`
+
+## Component Communication
+
+### Props (parent → child)
+Data flows down via Svelte `export let prop`
+
+### Events (child → parent)
+Children dispatch events via `createEventDispatcher()`
+
+### Public API (bind:this)
+Parent gets imperative handle via `bind:this={ref}` and calls:
+- `ref.publicMethod(args)` — guard with optional chaining: `ref?.method?.(args)`
+
+## Component Reference
+
+### OverviewTab (`lib/components/OverviewTab.svelte`)
+**Props**: `selectedNode`, `notes`, `worklog`, `formatDate`, `nodeKindLabel`
+**Events**: `createNote`, `addFile`, `createAction`, `switchTab`, `openNote`
+**State**: None (pure display)
+
+### NotesTab (`lib/components/notes/NotesTab.svelte`)
+**Props**: `notes`, `formatDate`
+**Events**: `submitCreateNote`({title}), `openNote`({note}), `startRename`({noteId, currentTitle}), `deleteNote`({note})
+**State**: `showCreateNote`, `newNoteTitle`
+
+### FilesTab (`lib/components/files/FilesTab.svelte`)
+**Props**: `selectedNode`, `wailsCall`
+**Events**: `openNote`({id, title}), `refreshParent`({nodeId}), `error`({message})
+**Public API** (via bind:this):
+- `resetToNode(nodeId)` — reset to root of given node
+- `addFile()` — open file picker and import
+- `loadFolder(folderId)` — load folder contents
+- `openFileById(fileNodeId)` — find and preview file
+- `focusItem(nodeId)` — select item by ID
+- `handleFilesKeydown(e)` — delegate keyboard handling
+- `resetState()` — full reset (on node change)
+
+**Internal state** (owned by FilesTab, NOT accessible from App):
+- `loadingFiles`, `currentFolderId`, `folderStack`, `fileItems`
+- `previewItem`, `previewContent`, `previewLoading`, `previewError`
+- `clipboard`, `selectedIds`, `dragIds`
+- `importing`, `importSummary`, `showImportDialog`, `pendingImportPath`, `pendingImportParent`
+- `showRename`, `renameId`, `renameValue`, `renameError`
+- `showConfirm`, `confirmTitle`, `confirmMessage`, `confirmAction`, `cancelAction`
 
 ## State Ownership Rules
 
@@ -69,32 +119,20 @@ App.svelte is **NOT** responsible for:
 - `startupStatus`, `startupChecked`
 - Navigation state: `navHistory`, `restoringHistory`
 - Trash browser state: `trashInfo`, `trashCount`, `trashSelectedIds`, `trashFolderId`, `trashFolderStack`
+- Trash preview: `trashPreviewItem`, `trashPreviewContent`, `trashPreviewLoading`, `trashPreviewError`
 - Journal state: `journalRows`, `journalSummary`, filters
 - Worklog modal state: `showWorklogModal`, `wlModal*`
 - Inbox: `inboxNodes`, `localInboxNodes`, capture state
 - Links: `links`
 - Sync: `syncStatus`
 - `error` (global error banner)
+- `notes` (loaded by `loadTabData`, passed to NotesTab and OverviewTab as prop)
+- `worklog` (loaded by `loadTabData`, passed to OverviewTab as prop)
 
-### App.svelte must NOT directly own (after extraction):
-- Files tab internal state → `FilesTab.svelte`
-- Notes tab list UI state → `NotesTab.svelte`
-- Overview tab content → `OverviewTab.svelte`
-
-## Component Communication
-
-### Props (parent → child)
-Data flows down via Svelte `export let prop`
-
-### Events (child → parent)
-Children dispatch events via `createEventDispatcher()`
-- Suffix `:` in event names means handler in template: `on:openNote={handler}`, NOT call on mount
-- All events should use `e.detail` to pass data
-
-### Public API (bind:this)
-Parent gets imperative handle via `bind:this={ref}` and calls:
-- `ref.publicMethod(args)` — guard with optional chaining: `ref?.publicMethod?.(args)`
-- Methods are exposed via `export function` in child component
+### App.svelte must NOT directly reference:
+- Files tab internal state (all in FilesTab)
+- Notes tab create form state (showCreateNote, newNoteTitle — in NotesTab)
+- Any `fileItems`, `selectedIds`, `currentFolderId`, `folderStack`, etc.
 
 ## Services (Wails API)