feat(vision): consult_vision tool + vision settings API

Backend vision update (additive to [email protected] / [email protected],
no version bump).

Contracts mirrored (.dispatch/transport-contract.reference.md):
- VisionSettingsResponse + SetVisionSettingsRequest (GET/PUT /settings/vision).
- Delta note: read_image -> consult_vision; numbered placeholders; compaction.

Tool rendering (ChatView):
- read_image test -> consult_vision (rendering is generic by toolName).
- +2 tests: numbered-placeholder text chunk + [Compacted image] text chunk
  (both regular text chunks, render as-is — no special handling).

New vision feature library (src/features/vision/):
- logic/view-model.ts (32 tests): VisionSettings/VisionSettingsPatch types
  (consumer-defines-port), LoadVisionSettings/SaveVisionSettings ports +
  results, normalizeVisionSettings (network-seam coercion), parseImageLimit/
  imageLimitChanged, compactionModelOptions (vision-capable models via chat's
  public isVisionModel + Auto sentinel), round-trip helpers, imageLimitLabel.
- ui/VisionSettingsView.svelte (9 tests): imageLimit input + Save,
  compactionModel dropdown (Auto + vision-capable models), load-on-mount,
  save-on-change, error/saved feedback.
- index.ts.

Cross-unit seam: isVisionModel added to features/chat public index.ts
(additive); imported through the public surface, not internals.

Store wiring (src/app/store.svelte.ts):
- visionSettings state + refreshVisionSettings (GET /settings/vision,
  normalized at the seam) + setVisionSettings (PUT, partial, returns merged) +
  VisionSettingsResult; seeded on boot; exposed on AppStore. +4 store tests.

Mounted in App.svelte: new "Vision" sidebar view kind + VisionSettingsView
in viewContent (not conversation-scoped); load/save adapters; visionManifest.

Verification: svelte-check 0/0; vitest 948/948 (run twice, +47 since the
prior vision commit); biome clean; vite build OK. See backend-handoff.md §2j.

Not merged or pushed.

1 files changed, 30 insertions, 0 deletions

diff --git a/src/features/vision/index.ts b/src/features/vision/index.ts
new file mode 100644
index 0000000..6956d75
--- /dev/null
+++ b/src/features/vision/index.ts
@@ -0,0 +1,30 @@
+export type {
+  CompactionModelOption,
+  ImageLimitParse,
+  LoadVisionSettings,
+  LoadVisionSettingsResult,
+  SaveVisionSettings,
+  SaveVisionSettingsResult,
+  VisionSettings,
+  VisionSettingsPatch,
+} from "./logic/view-model";
+export {
+  AUTO_COMPACTION_MODEL,
+  compactionModelChanged,
+  compactionModelFromValue,
+  compactionModelOptions,
+  DEFAULT_IMAGE_LIMIT,
+  imageLimitChanged,
+  imageLimitLabel,
+  MAX_IMAGE_LIMIT,
+  normalizeVisionSettings,
+  parseImageLimit,
+  selectedCompactionValue,
+} from "./logic/view-model";
+export { default as VisionSettingsView } from "./ui/VisionSettingsView.svelte";
+
+/** Public module manifest — aggregated by the shell's "Loaded Modules" view. */
+export const manifest = {
+  name: "vision",
+  description: "Global vision settings (image compaction limit + model)",
+} as const;