fix: remove dead config fields — prefer_handoff (#667) and use_terminal_colors (#671)

Neither field had any code path that read it. Shipping config knobs
that do nothing trains users to mistrust config. Remove until the
implementation exists.

config.example.toml

@@ -229,7 +229,6 @@ osc8_links = true            # emit OSC 8 escapes around URLs (Cmd+click in iTer
 #                           # Override: `locale = "zh-Hans"` for Simplified Chinese regardless of OS locale.
 #                           # Also settable at runtime: /config locale zh-Hans
 #                           # Note: this only affects TUI labels/chrome — it does NOT change model output language.
-# use_terminal_colors = false  # set true to let your terminal's color scheme take full control
 
 # ─────────────────────────────────────────────────────────────────────────────────
 # Feature Flags

crates/tui/src/compaction.rs

@@ -38,10 +38,6 @@ pub struct CompactionConfig {
     /// logic at small fixture sizes can set this to `0` to disable the
     /// floor.
     pub auto_floor_tokens: usize,
-    /// When `Some(true)`, the engine prefers writing a handoff file over
-    /// running LLM-based compaction when context pressure triggers.
-    /// `None` / `Some(false)` means default compaction behaviour.
-    pub prefer_handoff: Option<bool>,
 }
 
 impl Default for CompactionConfig {
@@ -63,7 +59,6 @@ impl Default for CompactionConfig {
             model: DEFAULT_TEXT_MODEL.to_string(),
             cache_summary: true,
             auto_floor_tokens: MINIMUM_AUTO_COMPACTION_TOKENS,
-            prefer_handoff: None,
         }
     }
 }

crates/tui/src/config.rs

@@ -343,9 +343,6 @@ pub struct TuiConfig {
     /// label and ignore the escape. Defaults to `true`; set `false` for
     /// terminals that misrender the sequence.
     pub osc8_links: Option<bool>,
-    /// When true, TUI uses Color::Reset everywhere and defers all color decisions
-    /// to the terminal emulator. Useful for terminals with custom color schemes.
-    pub use_terminal_colors: Option<bool>,
 }
 
 /// Notification delivery method (mirrors `tui::notifications::Method`).