oikos-web: extract the client stack from dtoro/oikos

Phase 1 of the hexagonal-architecture plan (dtoro/oikos
plans/2026-08-15-hexagonal-architecture.md). Moves the delivery stack
for the control-room UI into its own repo with its own pipeline:

- web/ — Svelte 5 SPA, verbatim (vendor/ included)
- desktop/ — Wails v3 wrapper, updateURL repointed to
  dtoro/oikos-web releases
- compose/ — Dockerfile + Caddyfile, verbatim (the /wails/* 404 and
  asset no-fallback quirks are load-bearing)
- docker-compose.yml — single web service, same 8091:80 publish,
  mem/cpu limits, and restart policy as the oikos stack's web service
- scripts/deploy.sh — mirrors oikos deploy essentials: CI-green gate,
  TOCTOU guard, version-tagged oikos-web:v$VERSION, prune to 3
- cmd/webhook + scripts/install-webhook.sh — standalone push-to-deploy
  receiver on :9798 (env-only secrets, no Infisical dependency)
- CI: the web job from oikos's ci.yml + the desktop build/release
  workflow, path-adjusted

Own VERSION (0.33.0) with the same bump-on-main rule; starts above
oikos's 0.32.x so the desktop updater sees an upgrade.

web/src/lib/components/knowledge/WikiContextRail.svelte

@@ -0,0 +1,124 @@
+<script lang="ts">
+  // Right pane: the discovery half of the wiki. From any note you can walk
+  // to the entity it's about, and from there sideways to every other note
+  // that concerns the same entity or shares a tag — this is what makes the
+  // knowledge base a graph to browse rather than a flat list to scroll.
+  //
+  // "Related" and "tag neighbours" are derived client-side from the list
+  // already loaded by Knowledge.svelte (KnowledgeListItem carries `about`
+  // and `tags`), not a separate endpoint — with ~100 notes total, filtering
+  // an in-memory array is cheaper and simpler than a bespoke backlinks
+  // query, and it's exactly the same data WikiTree's group-by-entity/tag
+  // modes already use.
+  import type { KnowledgeListItem } from '$lib/api'
+  import { openEntityWindow } from '$lib/stores/windows'
+  import DetailSection from '$lib/components/DetailSection.svelte'
+  import { kindMeta } from './kinds'
+  import LinkIcon from '@lucide/svelte/icons/link'
+
+  let {
+    item,
+    allItems,
+    onSelect
+  }: {
+    item: KnowledgeListItem | null
+    allItems: KnowledgeListItem[]
+    onSelect: (slug: string) => void
+  } = $props()
+
+  const related = $derived.by(() => {
+    if (!item || item.about.length === 0) return []
+    const aboutSet = new Set(item.about)
+    return allItems
+      .filter((it) => it.slug !== item.slug && it.about.some((s) => aboutSet.has(s)))
+      .sort((a, b) => b.updated_at.localeCompare(a.updated_at))
+  })
+
+  const tagNeighbours = $derived.by(() => {
+    if (!item || item.tags.length === 0) return []
+    const tagSet = new Set(item.tags)
+    return allItems
+      .filter((it) => it.slug !== item.slug && it.tags.some((t) => tagSet.has(t)))
+      .sort((a, b) => b.updated_at.localeCompare(a.updated_at))
+      .slice(0, 20) // common tags (e.g. "backup") can otherwise pull in most of the KB
+  })
+</script>
+
+<div class="flex h-full flex-col gap-2 overflow-y-auto pr-1">
+  {#if !item}
+    <p class="py-8 text-center text-xs text-muted-foreground">Nothing selected.</p>
+  {:else}
+    <DetailSection title="About" count={item.about.length} defaultOpen={true}>
+      {#if item.about.length === 0}
+        <p class="text-xs text-muted-foreground">Not linked to any entity.</p>
+      {:else}
+        <div class="flex flex-col gap-0.5">
+          {#each item.about as slug (slug)}
+            <button
+              type="button"
+              class="flex items-center gap-1.5 rounded px-1 py-0.5 text-left font-mono text-xs text-muted-foreground hover:bg-muted/50 hover:text-foreground"
+              onclick={() => openEntityWindow(slug)}
+            >
+              <LinkIcon class="size-3 shrink-0" />
+              <span class="truncate">{slug}</span>
+            </button>
+          {/each}
+        </div>
+      {/if}
+    </DetailSection>
+
+    <DetailSection
+      title="Also about these entities"
+      count={related.length}
+      defaultOpen={related.length > 0}
+    >
+      {#if related.length === 0}
+        <p class="text-xs text-muted-foreground">No other notes share a linked entity.</p>
+      {:else}
+        <div class="flex flex-col gap-0.5">
+          {#each related as it (it.slug)}
+            {@const Icon = kindMeta(it.kind).icon}
+            <button
+              type="button"
+              class="group flex items-center gap-1.5 rounded px-1 py-1 text-left text-xs hover:bg-muted/50"
+              onclick={() => onSelect(it.slug)}
+              title={it.title}
+            >
+              <Icon class="size-3 shrink-0 text-muted-foreground/70" />
+              <span class="min-w-0 flex-1 truncate group-hover:text-primary">{it.title}</span>
+            </button>
+          {/each}
+        </div>
+      {/if}
+    </DetailSection>
+
+    <!-- Only auto-open a *tight* neighbour set. A generic tag like "container"
+         is on 20 notes, and expanding all of those by default buries the
+         stronger entity-based links above it under a wall of weak matches;
+         a handful of shared-tag notes is a real cluster worth surfacing. -->
+    <DetailSection
+      title="Tag neighbours"
+      count={tagNeighbours.length}
+      defaultOpen={related.length === 0 && tagNeighbours.length > 0 && tagNeighbours.length <= 6}
+    >
+      {#if tagNeighbours.length === 0}
+        <p class="text-xs text-muted-foreground">No other notes share a tag.</p>
+      {:else}
+        <div class="flex flex-col gap-0.5">
+          {#each tagNeighbours as it (it.slug)}
+            {@const Icon = kindMeta(it.kind).icon}
+            <button
+              type="button"
+              class="group flex items-center gap-1.5 rounded px-1 py-1 text-left text-xs hover:bg-muted/50"
+              onclick={() => onSelect(it.slug)}
+              title={it.title}
+            >
+              <Icon class="size-3 shrink-0 text-muted-foreground/70" />
+              <span class="min-w-0 flex-1 truncate group-hover:text-primary">{it.title}</span>
+            </button>
+          {/each}
+        </div>
+      {/if}
+    </DetailSection>
+  {/if}
+</div>