Stage 4: restore the modern tree into app/skins/shadlike/

Both UIs now live side by side. The 18 modern component files come straight
from `git show main:<path>` — recovered, not rewritten, which is possible
because main's tip IS the merge base of this branch. There is no title-bar
among them: that component is win7-only, since the modern skin defers to the
native window frame.

Their imports were rewritten to @core the same way stage 1 did, leaving only
skin-internal relative imports behind. Added skins/shadlike/index.ts exporting
SHAD_ROOTS with the same shape as SEVEN_ROOTS, so main.ts can select a tree
without knowing either skin's internals.

Restored the skin axis in core/platform.ts, deleted in fe028a9 and needed
again by the modern tree: __APP_SKIN on the Window global, APP_SKIN,
IS_WIN7_CHROME, and IS_MAC_CHROME = IS_MAC && !IS_WIN7_CHROME. That last one
is what reserves pl-24 for the macOS traffic lights in the fused hiddenInset
header — and correctly stops reserving it under win7, where titleBarStyle
'hidden' removes the traffic lights entirely.

The tree is not reachable yet; the build is the gate. I checked that the gate
is real rather than assuming it: injecting a type error into an unreferenced
shadlike file does fail `bun run build:ui`, so ngtsc type-checks the whole
program including components nothing imports. Without that check, "the build
passes" would have proven nothing about 18 files no one references.

win7 remains pixel-identical to the pre-refactor baseline.

Co-Authored-By: Claude <noreply@anthropic.com>

ui/src/app/skins/shadlike/dialogs/chmod-dialog.ts

@@ -0,0 +1,129 @@
+import { Component, computed, inject, input, signal } from '@angular/core';
+import { I18nService } from '@core/i18n.service';
+import { DialogsService, type ChmodRequest } from '@core/dialogs.service';
+import { FocusService } from '@core/focus.service';
+
+const ROLES = ['roleOwner', 'roleGroup', 'roleOthers'] as const;
+const PERMS = ['r', 'w', 'x'] as const;
+
+@Component({
+  selector: 'app-chmod-dialog',
+  template: `
+    <div class="fixed inset-0 z-40 grid place-items-center bg-black/40" (mousedown)="cancel()">
+      <div
+        class="w-80 rounded-lg border border-border bg-card p-4 text-card-foreground shadow-xl"
+        (mousedown)="$event.stopPropagation()"
+        (keydown.escape)="cancel()"
+      >
+        <h2 class="text-sm font-semibold">{{ i18n.t('dialogs.chmodTitle') }}</h2>
+        <p class="mt-1 truncate text-xs text-muted-foreground">{{ targetLabel() }}</p>
+
+        <table class="mt-3 w-full text-xs">
+          <thead>
+            <tr class="text-muted-foreground">
+              <th class="pb-1 text-left font-normal"></th>
+              <th class="pb-1 font-normal">{{ i18n.t('dialogs.read') }}</th>
+              <th class="pb-1 font-normal">{{ i18n.t('dialogs.write') }}</th>
+              <th class="pb-1 font-normal">{{ i18n.t('dialogs.execute') }}</th>
+            </tr>
+          </thead>
+          <tbody>
+            @for (role of roles; track role; let r = $index) {
+              <tr>
+                <td class="py-1 pr-2 text-muted-foreground">{{ i18n.t('dialogs.' + role) }}</td>
+                @for (perm of perms; track perm; let p = $index) {
+                  <td class="py-1 text-center">
+                    <input
+                      type="checkbox"
+                      [checked]="hasBit(r, p)"
+                      (change)="toggleBit(r, p)"
+                      class="size-3.5 accent-primary"
+                    />
+                  </td>
+                }
+              </tr>
+            }
+          </tbody>
+        </table>
+
+        <div class="mt-3 flex items-center gap-2">
+          <label class="text-xs text-muted-foreground">{{ i18n.t('dialogs.octal') }}</label>
+          <input
+            [value]="octal()"
+            (input)="setOctal($any($event.target).value)"
+            maxlength="4"
+            spellcheck="false"
+            class="h-7 w-20 rounded-md border border-input bg-transparent px-2 font-mono text-xs outline-none focus:ring-2 focus:ring-ring"
+          />
+        </div>
+
+        <div class="mt-4 flex justify-end gap-2">
+          <button
+            (click)="cancel()"
+            class="rounded-md px-3 py-1.5 text-xs font-medium hover:bg-accent"
+          >
+            {{ i18n.t('common.cancel') }}
+          </button>
+          <button
+            (click)="submit()"
+            class="rounded-md bg-primary px-3 py-1.5 text-xs font-medium text-primary-foreground hover:bg-primary/90"
+          >
+            {{ i18n.t('common.apply') }}
+          </button>
+        </div>
+      </div>
+    </div>
+  `,
+})
+export class ChmodDialog {
+  readonly i18n = inject(I18nService);
+  readonly request = input.required<ChmodRequest>();
+
+  readonly roles = ROLES;
+  readonly perms = PERMS;
+
+  private readonly dialogs = inject(DialogsService);
+  private readonly focus = inject(FocusService);
+
+  // mode is initialized lazily from the request on first read
+  private readonly modeOverride = signal<number | null>(null);
+  readonly mode = computed(() => this.modeOverride() ?? this.request().initialMode & 0o777);
+  readonly octal = computed(() => this.mode().toString(8).padStart(3, '0'));
+
+  targetLabel(): string {
+    const targets = this.request().targets;
+    return targets.length === 1
+      ? targets[0]
+      : this.i18n.t('dialogs.chmodItems', { count: targets.length });
+  }
+
+  hasBit(role: number, perm: number): boolean {
+    return !!(this.mode() & (0o400 >> (role * 3 + perm)));
+  }
+
+  toggleBit(role: number, perm: number): void {
+    this.modeOverride.set(this.mode() ^ (0o400 >> (role * 3 + perm)));
+  }
+
+  setOctal(text: string): void {
+    if (/^[0-7]{1,4}$/.test(text)) {
+      this.modeOverride.set(parseInt(text, 8) & 0o777);
+    }
+  }
+
+  submit(): void {
+    const req = this.request();
+    const mode = this.mode();
+    this.close();
+    req.onConfirm(mode);
+  }
+
+  cancel(): void {
+    this.close();
+  }
+
+  private close(): void {
+    this.dialogs.chmod.set(null);
+    this.focus.bump();
+  }
+}