docs(user): dashboard, browsing, profile rewrites + new podcasts guide; trash stubs

Ground-truthed against the templates this pass:
- dashboard.md: real section kinds (system shelves incl. Continue
  Series, user collections, custom sections via /custom-section
  builder), Customize Dashboard panel semantics (per-library, drag,
  switches, 10-50 items, Save Changes), Refresh, This Week widget,
  per-item Read/Listen and progress-conflict resolve actions. The old
  page listed a wrong shelf set and never mentioned custom sections.
- library-browsing.md: the file was secretly titled 'Saving Custom
  Filters' and covered nothing else. Now the browsing page: All Books
  toolbar (search, Sort, Filters -> drawer hand-off, Save/Load/Clear
  saved filters), book detail as hub, series pages, podcasts split.
- profile-guide.md: field table ground-truthed from profile_form.templ
  (username/email DO remain editable there), audio defaults (speed,
  resume rewind, keep awake), timezone rendering contract, both theme
  doors (7-pick select vs 37-theme Appearance panel), Change Password
  with live checks, Danger Zone/Remove My Account + last-admin rule.
- podcasts.md NEW: the Podcasts page had zero documentation. Subscribing
  (Add Feed -> RSS URL, library, back-catalog download, download order,
  Add & Subscribe), Continue/All Feeds, Download All, player + Play as
  Sequence cross-link.
- Trashed user-areas.md, frontend-guide.md, settings-guide.md: stubs
  whose planned content now exists as real pages (or duplicates
  profile-guide). user-guide.md rewritten as the plain-language front
  door with a go-here-when table; index.md rows updated to match.
- ui-controls.md: 10 new gate-checked entries for every newly cited
  control (Add & Subscribe via templ-entity fragment).

docs/developer/ui-controls.md

@@ -27,6 +27,49 @@ Form-field labels inside a single modal (Name, Description…) are cited
 inline in docs and not tracked here; this list carries the controls people
 navigate by.
 
+## Dashboard, profile & podcasts
+
+```controls
+label: Customize Dashboard
+where: Library bar on the dashboard (button); opens the Customize Dashboard panel
+does: Opens per-library shelf arrangement — drag order, show/hide switches, items per section.
+
+label: Save Changes
+where: Customize Dashboard panel → submit
+does: Saves that library's shelf arrangement.
+
+label: Refresh
+where: Library bar on the dashboard (button)
+does: Re-reads libraries without a full page reload.
+note: icon button with a tooltip title
+
+label: Create Custom Section
+where: the custom-section builder page (/custom-section) → page title
+does: Page where a dashboard shelf is defined by filter rules or hand-picked books.
+
+label: Update Password
+where: profile page → Change Password → submit
+does: Saves the new password after live requirement checks.
+
+label: Remove My Account
+where: profile page → Danger Zone
+does: Deletes the account and all personal data after confirmation; blocked for the last admin.
+
+label: Add Feed
+where: Podcasts page
+does: Opens the Add Podcast Feed panel.
+
+label: Add & Subscribe
+where: Add Podcast Feed panel → submit
+does: Subscribes the feed and starts watching it for new episodes.
+also: Add & Subscribe
+note: templ source stores the ampersand entity; the rendered label reads "Add & Subscribe"
+
+label: Download all episodes now
+where: Add Podcast Feed panel
+does: Grabs the feed's back catalog immediately on subscribe.
+```
+
 ## Collections
 
 ```controls
@@ -127,7 +170,7 @@ where: Podcast page → episodes area
 does: Queues every episode of the feed for download.
 
 label: Download order
-where: Podcast page → feed settings
+where: Add Podcast Feed panel; podcast feed settings
 does: Sets the ordering used when feed episodes are downloaded.
 
 label: Match ALL / Group ANY header