feat(workspace,smart-scroll): per-conversation cwd + LSP view; smart auto-scroll

workspace ([email protected]): a cwd field in the Model sidebar view (GET/PUT /conversations/:id/cwd) + a new 'Language Servers' view (GET /conversations/:id/lsp) with per-server connected/starting/error badges, spinner, error text, and refresh. Store-owned reactive cwd, re-seeded on focus change; works for DRAFTS too (targets the draft's client-minted id, which survives promotion, so turn 1 runs in the chosen cwd). Network seam normalizes the untyped LSP body.

smart-scroll: pure stick-to-bottom reducer + injected controller shell (scroll/scrollend + a ResizeObserver on the content so the view follows async height changes — markdown/highlight, images, collapses, viewport reflow), plus a floating scroll-to-bottom button. FIX: restore the transcript scrollbar — the refactor moved overflow-y-auto to an inner child, so the flex-1 container needed min-h-0 to constrain instead of growing to content.

harness: vitest-setup polyfills Element.scrollTo + ResizeObserver (jsdom implements neither), fixing App component tests. docs: backend-handoff pruned (CR-3 resolved/removed); added cwd/LSP verification courier (backend confirmed all 6 asks ✅); removed the resolved cache-warming-timer courier.

Verified: svelte-check 0 errors, biome clean, 523 tests pass, vite build OK.

1 files changed, 36 insertions, 0 deletions

diff --git a/src/features/smart-scroll/ui/ScrollToBottom.svelte b/src/features/smart-scroll/ui/ScrollToBottom.svelte
new file mode 100644
index 0000000..6fbd326
--- /dev/null
+++ b/src/features/smart-scroll/ui/ScrollToBottom.svelte
@@ -0,0 +1,36 @@
+<script lang="ts">
+	// Thin affordance: a floating "scroll to bottom" button shown while the reader
+	// has scrolled up. Holds no logic — `show` and `onResume` come from the
+	// smart-scroll controller.
+	let {
+		show,
+		onResume,
+	}: {
+		show: boolean;
+		onResume: () => void;
+	} = $props();
+</script>
+
+<button
+	type="button"
+	class="btn btn-circle btn-sm absolute bottom-4 left-1/2 -translate-x-1/2 shadow-lg transition-opacity duration-200"
+	class:opacity-0={!show}
+	class:pointer-events-none={!show}
+	class:opacity-100={show}
+	onclick={onResume}
+	aria-label="Scroll to bottom"
+	aria-hidden={!show}
+	tabindex={show ? 0 : -1}
+>
+	<svg
+		xmlns="http://www.w3.org/2000/svg"
+		viewBox="0 0 24 24"
+		fill="none"
+		stroke="currentColor"
+		stroke-width="2.5"
+		class="size-4"
+		aria-hidden="true"
+	>
+		<path stroke-linecap="round" stroke-linejoin="round" d="M19 9l-7 7-7-7" />
+	</svg>
+</button>