feat(web): wire gerbview tool (file-less launch, wizard-skip, UI)

Register the newly WASM-ported Gerber Viewer in the web app the same way as
the other tools — registry entries only, no UI edits (ProjectDetailPage renders
launch links generically from FILELESS_TOOLS).

GERBVIEW_FRAME opens gerber/drill files through its own File→Open UI and projects
carry no gerber files to auto-open, so it's treated as file-less (boot standalone),
mirroring symbol_editor. It boots through single_top.cpp's STARTWIZARD, so it seeds
config to skip the first-run wizard (TOOL_NEEDS_CONFIG_SEED) and gets a
/usr/bin/gerbview argv0.

- contract: add "gerbview" to TOOLS, TOOL_LABELS ("Gerber Viewer"), FILELESS_TOOLS
- frontend: add gerbview to TOOL_ARGV0 and TOOL_NEEDS_CONFIG_SEED
- e2e: add file-less gerbview case to tools-open.spec.ts (title "Gerber Viewer",
  canvas painted, wizard-free, no WASM abort)

Verified in-browser via npm run test:web: gerbview boots wizard-free with the
viewer chrome (toolbars + layers manager), 0 console errors.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

web/apps/frontend/src/wasm/constants.ts

@@ -26,6 +26,7 @@ export const TOOL_ARGV0: Record<Tool, string> = {
   calculator: "/usr/bin/pcb_calculator",
   pl_editor: "/usr/bin/pl_editor",
   symbol_editor: "/usr/bin/symbol_editor",
+  gerbview: "/usr/bin/gerbview",
 };
 
 /**
@@ -43,6 +44,7 @@ export const TOOL_NEEDS_CONFIG_SEED: Record<Tool, boolean> = {
   calculator: true,
   pl_editor: true,
   symbol_editor: true,
+  gerbview: true,
 };
 
 /** KiCad user settings dir for this build (PATHS::GetUserSettingsPath()). */

web/packages/contract/src/schemas.ts

@@ -7,6 +7,7 @@ export const TOOLS = [
   "calculator",
   "pl_editor",
   "symbol_editor",
+  "gerbview",
 ] as const;
 export const toolSchema = z.enum(TOOLS);
 export type Tool = z.infer<typeof toolSchema>;
@@ -18,6 +19,7 @@ export const TOOL_LABELS: Record<Tool, string> = {
   calculator: "PCB Calculator",
   pl_editor: "Drawing Sheet Editor",
   symbol_editor: "Symbol Editor",
+  gerbview: "Gerber Viewer",
 };
 
 /** Default file-extension → tool mapping (the explicit URL segment always wins). */
@@ -31,10 +33,13 @@ export const EXTENSION_TOOL: Record<string, Tool> = {
  * Tools that do not take a file (booted standalone). The calculator has no file
  * concept; the symbol editor opens libraries through its own UI (its frame does
  * not implement OpenProjectFiles), so we boot it standalone rather than auto-open.
+ * The gerber viewer likewise opens gerber/drill files through its own File→Open
+ * UI — projects carry no gerber files to auto-open — so it boots standalone too.
  */
 export const FILELESS_TOOLS: ReadonlySet<Tool> = new Set<Tool>([
   "calculator",
   "symbol_editor",
+  "gerbview",
 ]);
 
 export const projectSlugSchema = z