style(tui): kill remaining blue + thinking-current into pane (v0.6.1)

Three operator-flagged issues:

## 1. "Background is still blue" — Header sub-widgets + scrollbar

Two surviving blue sources after v0.6.0:

- **Header sub-widgets** (HeaderIcon, HeaderTitle, HeaderClock) each
  carry their own `$primary` tint that the parent
  `Header { background }` rule alone doesn't override. Sub-selectors
  added: `Header, HeaderIcon, HeaderTitle, HeaderClock { background:
  $surface; color: $au-bright-blue; }`.
- **Scrollbar gutter** uses Textual's `$primary-tint` (#32436a) by
  default. Per-widget scrollbar overrides: `ListView` (picker) and
  `RichLog` (every pane) get explicit Sea darks for gutter + thumb.

Live verification: both AgentPickerApp and RatatoskrApp now render
ZERO instances of `#6388d8` (Aurora blue) or `#32436a` (its dark
derivative) in the export-screenshot SVG.

## 2. "Picker is bright cyan with unreadable text" — ListView focus

Textual's default `ListView:focus > ListItem.--highlight { background:
$primary }` was overriding my v0.6.0 `#agent-list > ListItem.--highlight
{ background: $au-dark-30 }` because `:focus` carries higher
specificity. The highlighted item was rendering with Aurora-blue
background + bright-blue text = unreadable.

Fix: both selectors targeted explicitly with sufficient specificity:
`ListView > ListItem.--highlight, ListView:focus > ListItem.--highlight
{ background: $au-dark-30 }`. Description text bumped to Sea bright-70
for better contrast against the dark-30 highlight.

## 3. "Streaming everywhere, should just stream in line"

User flagged the disconnect: live thinking rendered above the
TabbedContent in the right-column header, then on closure the content
"moved" to thinking-log inside the Thinking pane. Read as jarring
discontinuity.

Fix: `thinking-current` Static moved INTO the Thinking TabPane (docked
bottom), below `thinking-log`. Both surfaces co-located now — live
streaming + closed runs share the same pane. Operator switches to
Ctrl+3 (Thinking) to see chronological closed runs ABOVE + live
streaming line BELOW. Same pattern as the transcript: closed history
+ inline streaming tail.

Trade-off: live thinking is now visible only when on the Thinking
tab. Pre-v0.6.1 it was always visible above the tabs. The user
explicitly prefers the co-located shape; this is the right call.

## Contract amendment

docs/contracts/issues/13.contract.md INV-024 amended: thinking-current
now docks bottom of the Thinking TabPane (was right-column header).
v0.6.0 layout-spec snapshot updated to reflect the new shape. Drift-
check clean.

## Tests + smoke

241/241 GREEN; ruff clean. Live smoke against personal Worldtree
confirmed:
- thinking-current AND thinking-log both inside thinking-tab.walk_children().
- Post-Done state: 23 closed-run lines in thinking-log, thinking-current
  cleared to empty.
- Picker exports zero blue rects; main App exports zero blue rects.

Patch bump (v0.6.0 → v0.6.1): purely cosmetic + layout adjustment
within the existing pane structure; no public-API change.

persistent-memory.md

@@ -32,9 +32,9 @@ separate dev team rather than an in-tree Worldtree tool.
 
 ## Current state / in-flight
 
-_As of 2026-05-24 (post-v0.6.0 streaming + Thinking pane + turn headers):_
+_As of 2026-05-24 (post-v0.6.1 picker contrast + thinking inline):_
 
-**Status: v0.6.0 shipped.** Nine core issues complete (`sse_client`
+**Status: v0.6.1 shipped.** Nine core issues complete (`sse_client`
 #1, `sessions` #2, `cli` #3, `tui` #4, `--end-user-id` #5, TUI
 startup error visibility #6, presenter contract semantics amendment
 #12, startup agent picker #8, §5 layout reshape + Tools pane #13)
@@ -51,7 +51,8 @@ Static in the footer (static "Tools" v1; dynamic when more tabs
 land). CLI mode (--send) unaffected by design — INV-018.
 
 Last commits on `main`:
-- v0.6.0 refactor(tui): streaming Static + turn headers + Thinking pane + agent picker multi-line
+- v0.6.1 style(tui): kill remaining blue + thinking-current into Thinking pane
+- `cfee89a` refactor(tui): streaming + turn headers + Thinking pane (v0.6.0)
 - `7106af5` style(tui): UI polish pass — terminal label colors, placeholders (v0.5.1)
 - `ffd22fb` refactor(tui): content-only main pane + Debug tab + chrome dark (v0.5.0)
 - `2756f5f` style(tui): apply Australis theme to TUI chrome + widgets (v0.4.1)