feat(chat): full-bleed agent replies behind a chat style setting (issue #866) (#878)

* feat(chat): ChatStyle preference type + store field + AuthManager (issue #866)

* feat(settings): chat style toggle in Appearance (issue #866)

* feat(chat): plumb ChatStyle into ChatUiState + refreshSettings (issue #866)

* feat(chat): full-bleed turn grouping (issue #866)

* feat(chat): full-bleed agent message renderer (issue #866)

* feat(chat): full-bleed compact tool rows + system events (issue #866)

* feat(chat): full-bleed chat list renderer + streaming (issue #866)

* feat(chat): wire full-bleed renderer behind chat style setting (issue #866)

* test(theme): full-bleed contrast gate across all presets (issue #866)

Gate caught NORD light primary/background < 3:1 — header role label
switched to onSurfaceVariant (meta token, correct for header + passes
in every preset; NORD's pastel Frost accent can't reach 3:1 on light).

* test(chat): full-bleed renderer coverage (issue #866)

* style(chat): ktlint formatting pass on full-bleed renderer (issue #866)

* fix(chat): eagerly capture per-item state in full-bleed list (issue #866)

LazyColumn item{} lambdas run at composition time, so loop locals read
inside them saw final values: turn header never rendered (firstProseSeen
always true at compose) and milestones misindexed. Capture showTurnHeader
+ milestone as immutable vals during the DSL loop. Caught by fresh-context
review (decompiled Compose foundation to confirm item composition timing).

* test(chat): stub AuthManager.getChatStyle in mockkObject setups (issue #866)

refreshSettings()/loadSettings() now read AuthManager.getChatStyle();
the four test files that mockkObject(AuthManager) with explicit stubs
had no stub for the new method, so mockk fell through to the real
object and threw 'AuthManager not initialized'. Full suite: 953/953
passing, same shape as pristine origin/main.

* feat(settings): move chat style toggle from Appearance to Chat section

* feat(chat): hoist reasoning above tool rows in full-bleed turns

Tool rows stream in before the answer message, so the turn rendered
tools above the reasoning card. The turn's reasoning now renders at
the top of the agent turn, with tool rows and prose underneath.

Streaming is folded into the turn model (groupIntoTurnsWithStreaming)
so the hoist works live while the answer is still streaming, and the
detached streaming item is gone (which also fixed the duplicate
turn-header quirk for streaming continuations).

* feat(chat): cap reasoning card height + long-press to copy

Expanded trace caps at 40% of the screen with internal scroll (Show
full lifts the cap); long-press anywhere copies the reasoning.

* feat(chat): blinking typing caret while streaming

* feat(chat): make full-bleed the default chat style

* feat(chat): remove thinking dots, show agent header above reasoning

---------

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

app/src/test/java/com/m57/hermescontrol/theme/ThemePaletteTest.kt

@@ -45,6 +45,35 @@ class ThemePaletteTest {
         }
     }
 
+    /**
+     * Full-bleed chat renderer gate (issue #866): agent prose renders directly
+     * on the screen background (HermesScaffold containerColor = background),
+     * so the full-bleed text pairs must hold against [ColorScheme.background]:
+     * - body prose (onSurface) >= 4.5:1 — primary content, WCAG AA text
+     * - header role label + timestamp (onSurfaceVariant) >= 3:1 — WCAG AA UI
+     * (The header deliberately avoids `primary`: Nord's light mode reuses its
+     * pastel Frost accent as primary, which cannot reach 3:1 on a light
+     * background.)
+     * Iterates ThemePreset.entries directly so EVERY shipped preset (incl.
+     * NORD, which the [themes] list above predates) is covered.
+     */
+    @Test
+    fun fullBleedTextPairsMeetContrastInEveryShippedMode() {
+        ThemePreset.entries.forEach { preset ->
+            listOf(true, false).forEach { dark ->
+                val scheme = resolveColorScheme(preset, darkTheme = dark) ?: return@forEach
+                assertTrue(
+                    "$preset dark=$dark onSurface/background contrast must be >= 4.5:1 (full-bleed prose)",
+                    contrast(scheme.onSurface, scheme.background) >= 4.5f,
+                )
+                assertTrue(
+                    "$preset dark=$dark onSurfaceVariant/background contrast must be >= 3:1 (full-bleed header)",
+                    contrast(scheme.onSurfaceVariant, scheme.background) >= 3f,
+                )
+            }
+        }
+    }
+
     @Test
     fun amoledShipsDarkOnly() {
         assertTrue("AMOLED must ship a dark scheme", AmoledTheme.darkScheme != null)