test(determinism): deterministic waits + stableShot screenshots; drop blind sleeps/ifs/retries

Make the Playwright e2e + kicad suites deterministic so screenshot flake stops
tracing to timing races.

- Blind page.waitForTimeout -> condition waits (expect.poll, web-first
  assertions, waitUntil) + readiness helpers (waitForWxApp, waitForCanvasApp).
  Remaining sleeps are documented interaction dwells (annotated).
- Defensive "if element exists" branches -> loud asserts; label-fallback chains
  -> normalized clickMenuItemByText. First-run wizard for/if loops removed by
  seeding calculator/gerbview/pcbnew HTMLs.
- Screenshots: new stableShot(page, name) settles the render in-page (canvas
  hash over rAF) then writes a raw PNG to test-results/ for the existing offline
  gate (tools/screenshots vs baseline-screenshots). Replaces toHaveScreenshot,
  which did inline compare + its own baselines and had decoupled the specs from
  the real gate. scale:'css' pinned.
- retries: 0 in both configs.
- Guard: tests/tools/lint-determinism.ts (npm run lint:determinism) bans blind
  sleeps / toHaveScreenshot / inline retries / swallowed catches in specs;
  documented exceptions carry a marker. Rules in tests/TESTING.md.

Assertions, coverage, and renders unchanged (semantic-equivalence reviewed;
captures pixel-identical modulo inherent timer/timestamp/3d-raytrace variance).
Both suites green at retries:0 (e2e 340, kicad 92); ~35-61% faster.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BVX1pHMvRPYHdp6ZfEawrk

tests/apps/kicad/calculator.html

@@ -120,10 +120,42 @@
       }
     };
 
+    // Land the user in a sane, writable directory instead of MEMFS root.
+    var setupHomeDir = function() {
+      var home = '/home/kicad';
+      FS.mkdirTree(home);
+      FS.chdir(home);
+      console.log('[KICAD] cwd set to ' + home);
+    };
+
+    // single_top.cpp runs STARTWIZARD on launch: a modal first-run "Setup"
+    // wizard shown whenever the settings dir lacks a kicad_common.json or valid
+    // global library tables. In this ephemeral MEMFS that is EVERY load. Seed a
+    // minimal default config before main() so every provider reports
+    // NeedsUserInput()==false and the wizard never opens — same as eeschema.html
+    // and pl_editor.html.
+    var seedKicadConfig = function() {
+      var cfgDir = '/home/kicad/.config/kicad/kicad/9.99';
+      FS.mkdirTree(cfgDir);
+
+      var writeIfAbsent = function(path, contents) {
+        try { FS.stat(path); return; } catch (e) { /* absent — seed it */ }
+        FS.writeFile(path, contents);
+        console.log('[KICAD] Seeded ' + path);
+      };
+
+      writeIfAbsent(cfgDir + '/kicad_common.json', JSON.stringify({
+        do_not_show_again: { update_check_prompt: true, data_collection_prompt: true }
+      }, null, 2));
+      writeIfAbsent(cfgDir + '/sym-lib-table', '(sym_lib_table\n  (version 7)\n)\n');
+      writeIfAbsent(cfgDir + '/fp-lib-table', '(fp_lib_table\n  (version 7)\n)\n');
+      writeIfAbsent(cfgDir + '/design-block-lib-table', '(design_block_lib_table\n  (version 7)\n)\n');
+    };
+
     var Module = {
       thisProgram: '/usr/bin/pcb_calculator',  // argv[0]
 
-      preRun: [createCanvas, writeResources],
+      preRun: [createCanvas, writeResources, setupHomeDir, seedKicadConfig],
       postRun: [],
 
       print: function(text) {

tests/apps/kicad/gerbview.html

@@ -123,10 +123,31 @@
       console.log('[KICAD] cwd set to ' + home);
     };
 
+    // Seed a minimal default config before main() so STARTWIZARD finds
+    // NeedsUserInput()==false and the first-run setup wizard never opens —
+    // same as eeschema.html / pl_editor.html.
+    var seedKicadConfig = function() {
+      var cfgDir = '/home/kicad/.config/kicad/kicad/9.99';
+      FS.mkdirTree(cfgDir);
+
+      var writeIfAbsent = function(path, contents) {
+        try { FS.stat(path); return; } catch (e) { /* absent — seed it */ }
+        FS.writeFile(path, contents);
+        console.log('[KICAD] Seeded ' + path);
+      };
+
+      writeIfAbsent(cfgDir + '/kicad_common.json', JSON.stringify({
+        do_not_show_again: { update_check_prompt: true, data_collection_prompt: true }
+      }, null, 2));
+      writeIfAbsent(cfgDir + '/sym-lib-table', '(sym_lib_table\n  (version 7)\n)\n');
+      writeIfAbsent(cfgDir + '/fp-lib-table', '(fp_lib_table\n  (version 7)\n)\n');
+      writeIfAbsent(cfgDir + '/design-block-lib-table', '(design_block_lib_table\n  (version 7)\n)\n');
+    };
+
     var Module = {
       thisProgram: '/usr/bin/gerbview',  // Fake absolute path for argv[0]
 
-      preRun: [createCanvas, writeResources, setupHomeDir],
+      preRun: [createCanvas, writeResources, setupHomeDir, seedKicadConfig],
       postRun: [],
 
       print: function(text) {

tests/apps/kicad/pcbnew.html

@@ -120,6 +120,35 @@
       }
     };
 
+    // Land in a sane, writable cwd instead of MEMFS root.
+    var setupHomeDir = function() {
+      var home = '/home/kicad';
+      FS.mkdirTree(home);
+      FS.chdir(home);
+      console.log('[KICAD] cwd set to ' + home);
+    };
+
+    // Seed a minimal default config before main() so STARTWIZARD finds
+    // NeedsUserInput()==false and the first-run setup wizard never opens —
+    // same as eeschema.html / pl_editor.html.
+    var seedKicadConfig = function() {
+      var cfgDir = '/home/kicad/.config/kicad/kicad/9.99';
+      FS.mkdirTree(cfgDir);
+
+      var writeIfAbsent = function(path, contents) {
+        try { FS.stat(path); return; } catch (e) { /* absent — seed it */ }
+        FS.writeFile(path, contents);
+        console.log('[KICAD] Seeded ' + path);
+      };
+
+      writeIfAbsent(cfgDir + '/kicad_common.json', JSON.stringify({
+        do_not_show_again: { update_check_prompt: true, data_collection_prompt: true }
+      }, null, 2));
+      writeIfAbsent(cfgDir + '/sym-lib-table', '(sym_lib_table\n  (version 7)\n)\n');
+      writeIfAbsent(cfgDir + '/fp-lib-table', '(fp_lib_table\n  (version 7)\n)\n');
+      writeIfAbsent(cfgDir + '/design-block-lib-table', '(design_block_lib_table\n  (version 7)\n)\n');
+    };
+
     var Module = {
       thisProgram: '/usr/bin/pcbnew',  // Fake absolute path for argv[0] (KiCad DEBUG check)
 
@@ -128,7 +157,7 @@
       // FRAME_PCB_EDITOR at runtime.
       arguments: ['--frame=pcb'],
 
-      preRun: [createCanvas, writeResources],
+      preRun: [createCanvas, writeResources, setupHomeDir, seedKicadConfig],
       postRun: [],
 
       print: function(text) {