chore(studio): remove fully rolled-out studio feature flags (#2889)

## What

Removes six Studio feature flags that have been default-`true` for 7+ weeks. Each is reachable under two env names, so this deletes **12 `VITE_STUDIO_*` env vars**:

| Flag constant | Env names removed | Default-on since |
|---|---|---|
| `STUDIO_PREVIEW_MANUAL_EDITING_ENABLED` | `VITE_STUDIO_ENABLE_PREVIEW_MANUAL_DRAGGING`, `VITE_STUDIO_PREVIEW_MANUAL_EDITING_ENABLED` | 2026-05-12 |
| `STUDIO_INSPECTOR_PANELS_ENABLED` (+ its `STUDIO_PREVIEW_SELECTION_ENABLED` alias) | `VITE_STUDIO_ENABLE_INSPECTOR_PANELS`, `VITE_STUDIO_INSPECTOR_PANELS_ENABLED` | 2026-05-12 |
| `STUDIO_BLOCKS_PANEL_ENABLED` | `VITE_STUDIO_ENABLE_BLOCKS_PANEL`, `VITE_STUDIO_BLOCKS_PANEL_ENABLED` | 2026-05-18 |
| `STUDIO_GSAP_PANEL_ENABLED` | `VITE_STUDIO_ENABLE_GSAP_PANEL`, `VITE_STUDIO_GSAP_PANEL_ENABLED` | 2026-05-28 |
| `STUDIO_KEYFRAMES_ENABLED` | `VITE_STUDIO_ENABLE_KEYFRAMES`, `VITE_STUDIO_KEYFRAMES_ENABLED` | 2026-06-05 |
| `STUDIO_RAZOR_TOOL_ENABLED` | `VITE_STUDIO_ENABLE_RAZOR_TOOL`, `VITE_STUDIO_RAZOR_TOOL_ENABLED` | 2026-06-10 |

## Why

Every one of these shipped as a rollout gate, went to `true`, and then stayed. Because none of them was ever flipped back, the `false` branch was unreachable in practice while still costing a real import, a real conditional, and a real "what happens if this is off?" question at ~90 call sites across 25 files.

The bigger cost is what the dead branch kept alive. Removing the flags also removes the disabled-Studio code paths that only existed to serve them:

- the greyed-out, `disabled`, "Manual editing is temporarily disabled" Inspector button in `StudioHeader` (and the `STUDIO_MANUAL_EDITING_DISABLED_TITLE` constant behind it)
- the inspector-off reset `useEffect` in `useDomSelection`, which force-cleared selection and redirected the right panel to Renders
- three selection kill-switch early-returns in `useDomSelection` (`applyDomSelection`, `handleTimelineElementSelect`, `applyMarqueeSelection`)
- the tab-redirect branch in `normalizeStudioUrlPanelTab`, whose `options.inspectorPanelsEnabled` parameter had no production caller at all (only tests passed it)

## How

No behavior change: every flag was removed by keeping its default-`true` side.

The call-site edits are three mechanical boolean shapes (`X && rest` → `rest`, `rest && X` → `rest`, `!X || rest` → `rest`), applied by script for uniformity. Everything else (ternaries, `if` guards, unreachable blocks, JSX wrappers that had no other condition) was done by hand and the whole diff was read line by line afterwards.

`resolveStudioBooleanEnvFlag` and the `import.meta.env` / `window.__HF_STUDIO_ENV__` plumbing stay: three flags still use them (`STUDIO_FLAT_INSPECTOR_ENABLED`, `STUDIO_SDK_CUTOVER_ENABLED`, `STUDIO_SDK_RESOLVER_SHADOW_ENABLED`). Its unit tests kept their coverage but now exercise a live flag pair instead of retired env names, so no dead `VITE_STUDIO_*` string is left in the repo.

Net **-191 lines** (236 insertions, 427 deletions across 25 files); most insertions are reindentation of JSX that lost a wrapper.

### Deliberately not in scope

Flags authored by other people are untouched, even where they look similarly settled:

- `VITE_STUDIO_ENABLE_FLAT_INSPECTOR` / `VITE_STUDIO_FLAT_INSPECTOR_ENABLED` (default true, but not mine)
- `VITE_STUDIO_SDK_CUTOVER_ENABLED`, `VITE_STUDIO_SDK_CUTOVER_FAMILIES`, `VITE_STUDIO_SDK_RESOLVER_SHADOW_ENABLED` (SDK cutover canary, still soaking)
- `VITE_HYPERFRAMES_NO_TELEMETRY`

Mine but genuinely long-lived configuration rather than rollout gates, so they stay: `VITE_STUDIO_DISCOVERY_PORTS`, `VITE_HYPERFRAMES_FEEDBACK_INTERVAL`, `VITE_HYPERFRAMES_NO_FEEDBACK` (a documented user opt-out), plus the `HYPERFRAMES_*` binary paths, API URLs, cache sizes, and timeouts.

`VITE_STUDIO_ENABLE_MOTION_PANEL` / `VITE_STUDIO_MOTION_PANEL_ENABLED` were already retired from production code before this PR; they only survived as placeholder names inside the resolver's unit tests, and this PR swaps those out.

## Test plan

- [x] Unit tests added/updated - dropped the two tests asserting removed flag defaults; retargeted the `resolveStudioBooleanEnvFlag` cases at a live flag pair; updated `studioUrlState` tests for the narrowed `normalizeStudioUrlPanelTab` signature (now also asserts an unknown tab returns `null`).
- [x] Manual testing performed - see below.
- [ ] Documentation updated (if applicable) - not needed; no removed name appears in `docs/`, `skills/`, or `registry/`. (`docs/changelog.mdx` has one historical entry naming `STUDIO_KEYFRAMES_ENABLED`; changelog history is left as written.)

```
packages/studio: bunx vitest run          # 280 files, 3116 tests pass, 1 skipped
packages/studio: bunx tsc --noEmit        # clean
bun run build                             # green (all packages)
bunx oxlint  <25 changed files>           # 0 warnings, 0 errors
bunx oxfmt --check <25 changed files>     # clean
```

Two extra checks, because part of this diff was script-generated:

1. Zero references to any removed flag constant or env name remain anywhere outside `docs/changelog.mdx`.
2. Diffed every string literal in each changed non-test file against `origin/main`. The only differences are the intended removals: the 12 env names, `"Manual editing is temporarily disabled"`, the `"cursor-not-allowed …"` disabled class, the 3-column `"1fr 1fr 1fr"` grid, and the `"renders"` redirect literals. No user-facing label, tooltip, or class string changed by accident.

packages/studio/src/utils/studioUrlState.test.ts

@@ -34,12 +34,8 @@ describe("resolveMasterCompositionPath", () => {
 
 describe("normalizeStudioUrlPanelTab", () => {
   it("accepts slideshow and variables as valid tabs", () => {
-    expect(normalizeStudioUrlPanelTab("slideshow", { inspectorPanelsEnabled: true })).toBe(
-      "slideshow",
-    );
-    expect(normalizeStudioUrlPanelTab("variables", { inspectorPanelsEnabled: true })).toBe(
-      "variables",
-    );
+    expect(normalizeStudioUrlPanelTab("slideshow")).toBe("slideshow");
+    expect(normalizeStudioUrlPanelTab("variables")).toBe("variables");
   });
 });
 
@@ -184,9 +180,10 @@ describe("studio url state", () => {
     ).toBe("compositions/title.html");
   });
 
-  it("normalizes url tabs against feature flags", () => {
+  it("passes through every valid tab and rejects unknown ones", () => {
     expect(normalizeStudioUrlPanelTab("renders")).toBe("renders");
-    expect(normalizeStudioUrlPanelTab("layers", { inspectorPanelsEnabled: false })).toBe("renders");
+    expect(normalizeStudioUrlPanelTab("layers")).toBe("layers");
+    expect(normalizeStudioUrlPanelTab("nope" as never)).toBeNull();
   });
 
   it("hydrates seek first, preserves the initial url state, then restores selection", async () => {

packages/studio/src/utils/studioUrlState.ts

@@ -1,6 +1,5 @@
 import type { RightPanelTab } from "./studioHelpers";
 import { buildProjectHash, parseProjectHashRoute } from "./projectRouting";
-import { STUDIO_INSPECTOR_PANELS_ENABLED } from "../components/editor/manualEditingAvailability";
 import { roundTo3 } from "./rounding";
 
 export interface StudioUrlSelectionState {
@@ -34,17 +33,9 @@ export function resolveMasterCompositionPath(fileTree: string[]): string | null
   return fileTree.find((p) => p.endsWith(".html")) ?? null;
 }
 
-export function normalizeStudioUrlPanelTab(
-  tab: RightPanelTab | null,
-  options: {
-    inspectorPanelsEnabled?: boolean;
-  } = {},
-): RightPanelTab | null {
+export function normalizeStudioUrlPanelTab(tab: RightPanelTab | null): RightPanelTab | null {
   if (!tab) return null;
   if (!VALID_TABS.includes(tab)) return null;
-  const inspectorPanelsEnabled = options.inspectorPanelsEnabled ?? STUDIO_INSPECTOR_PANELS_ENABLED;
-
-  if (!inspectorPanelsEnabled && tab !== "renders") return "renders";
   return tab;
 }