Reconcile the frontend with the round-1 backend contracts

Five backend branches merged and the TypeScript still compiled, because
none of this is a type error: a field that arrives `undefined`, a variant
nothing emits any more, a prompt whose loop never closes. Six things.

**Orphaned volumes are destructive now, not safe.** `ReclaimTarget::
OrphanVolume` is gone from Rust; the object is a `DestructiveTarget::
OrphanVolume { name, project_id }` confirmed against the *volume's* name,
there being no project to name. The TS union still listed it under
`ReclaimTarget`, and — worse — `DiskProjectTable` keys destructive items
off `project_id`, which an orphan's never matches. So the item existed in
the plan and appeared nowhere on screen. `DiskSettings` now splits the
plan's destructive list and gives orphans their own section with a
per-volume `TypedConfirmModal`. The copy says what a
`triple-c-claude-config-*` volume actually is — a Claude login
credential, every plugin and skill, every transcript that project had —
and keeps the sentence explaining that "no matching project" is a lookup
against the project list and is never inferred from a project being
stopped or having no image, which is the inference that once flagged two
live projects.

`TypedConfirmModal` grew a `subject` prop: asking a user for "the exact
project name" of a volume that has no project is asking for a string that
does not exist.

**Snapshot and Total reconcile.** `ProjectDiskRow.snapshot_attributed_bytes`
is the single figure `snapshot_attribution()` exists to produce. The
column rendered `snapshot_above_base_bytes` and fell back to `—` while
the Total was `size - shared` regardless — and in that branch `size -
shared` is the whole 4.7 GB base image, charged per project and then
added again as a base-image row. One field, one rule. The one branch
where the figure *is* the whole image says so rather than passing itself
off as a share.

**The overwrite loop closes.** Traced end to end: a `FILE_EXISTS:`
refusal raises the prompt, Replace re-invokes with `overwrite: true`,
Skip advances, "…all" answers the rest without asking, and picker and
host-drop both reach `uploadFileToContainer` through `uploadPaths`. Two
gaps: a second batch's `askOverwrite` overwrote the first's resolver,
leaving that batch awaiting an answer no dialog could produce; and the
backend's written refusals — a hidden host folder, a path outside the
write roots — were passed as a toast `detail`, which `ToastHost` renders
as collapsed monospace behind a "Details" button, so the only sentence
that explained anything was the part nobody saw. `readableRefusal`
promotes it to the headline when a batch failed the same way.

**The browser pane's sandbox is pinned.** `allow-same-origin` must stay
(the proxy's gate reads `Origin`/`Referer`, and an opaque origin sends
`null`); every top-navigation grant and `allow-popups-to-escape-sandbox`
must stay absent, and the test names the offending token rather than
printing a set diff.

**`@tauri-apps/plugin-store` is gone** from `package.json` — its
capability grants were removed as a host-file-write primitive and nothing
in `app/src` imports it. The lockfile was updated with
`--package-lock-only`, deliberately: `node_modules` is a symlink shared
with other worktrees and a real install would have pulled it out from
under them.

Nothing under `src-tauri/` is touched. 663 frontend tests pass (was 635),
`tsc --noEmit` clean, `npm run build` green, `cargo test` 446 unchanged.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GBq2rGum6GX7xXgsas1fDc

app/src/lib/uploadErrors.test.ts

@@ -1,8 +1,10 @@
 import { describe, expect, it } from "vitest";
 import {
+  errorText,
   FILE_EXISTS_MARKER,
   fileExistsPath,
   isFileExistsError,
+  readableRefusal,
 } from "./uploadErrors";
 
 /**
@@ -79,3 +81,68 @@ describe("fileExistsPath", () => {
     expect(fileExistsPath(null)).toBeNull();
   });
 });
+
+/**
+ * The other half of the contract: refusals that are *not* a name clash, but are
+ * a sentence the backend wrote for the person reading it. They used to arrive
+ * as a toast's `detail`, which renders as collapsed monospace behind a
+ * "Details" button — so the only part of the message that explained anything
+ * was the part nobody saw.
+ */
+describe("readableRefusal", () => {
+  const hidden =
+    '".ssh" is a hidden folder — Triple-C will not save there. Choose a visible location.';
+  const outside =
+    "Folder path is outside the folders this panel can change (/workspace, /home/claude, /tmp): /etc";
+
+  it("recognises the hidden-host-folder refusal, in both directions", () => {
+    expect(readableRefusal(hidden)).toBe(hidden);
+    expect(
+      readableRefusal('".aws" is a hidden folder — Triple-C will not read there. Choose a visible location.'),
+    ).toContain("hidden folder");
+  });
+
+  it("recognises the container write-root refusal", () => {
+    expect(readableRefusal(outside)).toBe(outside);
+  });
+
+  it("strips a wrapper a JS layer put in front of the sentence", () => {
+    // `invoke` rejects with the bare string today, but an `Error` anywhere in
+    // between would otherwise put "Error: " in front of prose meant to be read.
+    expect(readableRefusal(new Error(hidden))).toBe(hidden);
+    expect(readableRefusal(`Error: ${hidden}`)).toBe(hidden);
+    expect(readableRefusal(`Uncaught (in promise) Error: ${outside}`)).toBe(outside);
+    expect(readableRefusal({ message: `invoke failed: ${outside}` })).toBe(outside);
+  });
+
+  it("says nothing about failures that are not a written refusal", () => {
+    // Promotion is an improvement, not a fallback: anything unrecognised keeps
+    // reporting exactly as it did before.
+    expect(readableRefusal("File too large to upload (900 MB; limit 256 MB)")).toBeNull();
+    expect(readableRefusal("FILE_EXISTS: /workspace/a.txt already exists")).toBeNull();
+    expect(readableRefusal("cp: Permission denied")).toBeNull();
+    expect(readableRefusal(null)).toBeNull();
+  });
+});
+
+describe("errorText", () => {
+  it("keeps an ordinary message intact", () => {
+    expect(errorText("cp: cannot create regular file: Permission denied")).toBe(
+      "cp: cannot create regular file: Permission denied",
+    );
+  });
+
+  it("reads a message out of a shape `String()` would render as [object Object]", () => {
+    expect(errorText({ message: "Container not running" })).toBe("Container not running");
+    expect(errorText({ kind: "NotRunning" })).toBe("NotRunning");
+    expect(errorText(new Error("Failed to upload file to container: no space left"))).toBe(
+      "Failed to upload file to container: no space left",
+    );
+  });
+
+  it("prefers the written refusal when there is one", () => {
+    expect(errorText(new Error("Folder path is outside the folders this panel can change (/workspace): /etc"))).toBe(
+      "Folder path is outside the folders this panel can change (/workspace): /etc",
+    );
+  });
+});