Add web shell, build and deploy scripts, Playwright smoke

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

web/build.mjs

@@ -0,0 +1,36 @@
+// Builds web/dist; files under a/ are named by content.
+import { execFileSync } from 'node:child_process'
+import { createHash } from 'node:crypto'
+import { copyFileSync, mkdirSync, readFileSync, renameSync, rmSync, statSync, writeFileSync } from 'node:fs'
+import { dirname, join } from 'node:path'
+import { fileURLToPath } from 'node:url'
+
+const web = dirname(fileURLToPath(import.meta.url))
+const root = dirname(web)
+const dist = join(web, 'dist')
+
+rmSync(dist, { recursive: true, force: true })
+mkdirSync(join(dist, 'a'), { recursive: true })
+execFileSync('go', ['build', '-trimpath', '-ldflags=-s -w', '-tags', 'mygo_noinspector', '-o',
+  join(dist, 'app.wasm'), './cmd/gallery'], { cwd: root, stdio: 'inherit', env: { ...process.env, GOOS: 'js', GOARCH: 'wasm' } })
+const goroot = execFileSync('go', ['env', 'GOROOT'], { encoding: 'utf8' }).trim()
+copyFileSync(join(goroot, 'lib', 'wasm', 'wasm_exec.js'), join(dist, 'wasm_exec.js'))
+
+// name moves a file into a/ by its content hash.
+function name (base, file, ext) {
+  const hash = createHash('sha256').update(readFileSync(join(dist, file))).digest('hex').slice(0, 12)
+  const to = `a/${base}.${hash}.${ext}`
+  renameSync(join(dist, file), join(dist, to))
+  return to
+}
+
+const size = statSync(join(dist, 'app.wasm')).size
+const wasm = name('app', 'app.wasm', 'wasm')
+const exec = name('wasm_exec', 'wasm_exec.js', 'js')
+writeFileSync(join(dist, 'main.js'),
+  readFileSync(join(web, 'main.js'), 'utf8').replaceAll('__WASM__', wasm).replaceAll('__SIZE__', String(size)))
+const main = name('main', 'main.js', 'js')
+writeFileSync(join(dist, 'index.html'),
+  readFileSync(join(web, 'index.html'), 'utf8').replace('__EXEC__', exec).replace('__MAIN__', main))
+copyFileSync(join(web, '_headers'), join(dist, '_headers'))
+console.log(`web/dist built: ${main} ${wasm} (${size} bytes)`)