UI: mobile-friendly header — move backend/display into settings panel

Header trimmed to 4 buttons (Sessions, Files, ⚙, ?). Backend toggle,
font size, and theme moved into the ⚙ settings panel under new Backend
and Display sections. Panels use responsive widths to avoid overflow on
small screens. Mobile breakpoints tighten padding and hide subtitle.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

inara/HELP.md

@@ -12,12 +12,19 @@
 |---|---|
 | **Sessions** | Open the sessions panel — list, resume, or start sessions |
 | **Files** | Open the identity file editor (SOUL, MEMORY, etc.) |
-| **⚙ N** | Open the Context & Memory panel (N = current tier) |
-| **claude / gemini** | Active backend — click to toggle primary |
-| **Aa / A+ / A−** | Cycle font size: normal (16px) → large (18px) → small (14px) |
-| **☾ / ☀** | Toggle dark / light theme |
+| **⚙ N** | Open the Settings panel (N = current context tier) |
 | **?** | Open this help panel |
 
+The **⚙ Settings** panel contains all configuration options:
+
+| Section | Controls |
+|---|---|
+| **Context Tier** | T1 – T4 context depth |
+| **Memory Layers** | Toggle Long / Mid / Short memory on/off |
+| **Distill Memory** | Manually trigger short / mid / long / all distillation |
+| **Backend** | Active LLM backend — click to toggle claude ↔ gemini |
+| **Display** | Aa/A+/A− font size cycle · ☾/☀ theme toggle |
+
 All header settings (theme, font size, tier, memory layers) persist in `localStorage` across page refreshes.
 
 ---
@@ -58,7 +65,7 @@ Notes are injected into a session without triggering an LLM response.
 ## Backends
 
 - **Claude CLI** and **Gemini CLI** are both available. One is primary, the other is fallback.
-- Click the backend button (`claude` or `gemini`) to switch which is primary.
+- Click **⚙** → **Backend** to toggle between `claude` and `gemini` as the primary.
 - If the primary fails or times out, the fallback is used automatically. A **⚡** notice appears in the chat when this happens.
 - Timeouts: Claude 60s, Gemini 120s.