Merge branch 'main' into feature/techlog-ui-migration

Integrates the frontend template sync (a0fbafb → 5434760) into the TechLog UI
migration. Merged in this direction so every conflict is resolved and proved in
the worktree; main is only fast-forwarded afterwards and never holds a state
that was not verified here.

15 conflicts. The rule throughout: keep the template's mechanism, keep the
product's content, and never invent a third state neither branch would accept.

The template's product manifest and its runtime feature kill switch are adopted.
The route registry is deliberately not composed from contract.routes: the
reference feature still declares screens this product deleted, and reducing over
them would register paths with no component behind them. ROUTE_FEATURE_OWNER is
narrowed to registered routes for the same reason. The first resolution did
compose from contract.routes and was rejected by product-features.test.ts.

Three files pinned counts and a digest describing the gate contract. Neither
side's numbers describe the merged config/ci/gates.json, so they were recomputed
from it rather than chosen: 27 gates, 82 commands, 94 command references, 107
evidence references, 128 artifacts, shape sha256 5063586d.

README.md and docs/accessibility/manual-checklist.md now enumerate this
product's 27 routes, which the template's own verify:documentation requires.

product-feature-switch.test.tsx was rewritten around the invariant that still
applies here — no registered route without a component — rather than deleted
with the screens it used to exercise.

docs/operations/template-merge-2026-08-17.md records every decision, the gate
results, and the three follow-ups this merge deliberately did not decide.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

scripts/test-sample-removal.ts

@@ -27,10 +27,16 @@ const fixtureRoot = await mkdtemp(
 const pnpmCli = requireRemovalFixtureEnvironment("npm_execpath");
 const featureSource = "src/features/reference-feature";
 const featureTests = "tests/features/reference-feature";
+/**
+ * Platform tests that must survive the sample feature's removal. Asserting they
+ * are still present is what stops the removal fixture from "passing" by having
+ * quietly deleted the platform's own coverage along with the feature.
+ */
 const commonTestPaths = [
   "tests/unit/external-contract-runtime.test.ts",
   "tests/unit/http-execution-v3.test.ts",
   "tests/unit/runtime-adapters.test.ts",
+  "tests/integration/http-execution-v3-observability.test.ts",
 ];
 const featureOwnedPaths = [
   featureSource,
@@ -44,37 +50,6 @@ const featureOwnedPaths = [
   "tests/fixtures/typecheck/invalid-feature-input.ts",
   "tests/fixtures/typecheck/invalid-reference-operation.ts",
 ];
-const copyTargets = [
-  "src",
-  "tests",
-  "recipes",
-  "scripts",
-  "schemas",
-  "config",
-  "public",
-  ".gitea",
-  ".storybook",
-  "index.html",
-  "package.json",
-  "tsconfig.base.json",
-  "tsconfig.json",
-  "tsconfig.app.json",
-  "tsconfig.node.json",
-  "tsconfig.test.json",
-  "tsconfig.recipes.json",
-  "tsconfig.web-worker.json",
-  "tsconfig.service-worker.json",
-  "vite.service-worker.config.ts",
-  "vite.config.ts",
-  "vitest.config.ts",
-  "playwright.config.ts",
-  "playwright.dev.config.ts",
-  "playwright.storybook.config.ts",
-  "playwright.visual.config.ts",
-  "eslint.config.ts",
-  ".dependency-cruiser.json",
-  ".nvmrc",
-];
 
 const emptyContracts = `import type { RouteDefinition } from "../contracts/routes.ts";
 import { PLATFORM_SCHEMA_REGISTRY } from "../contracts/schema-registry.ts";
@@ -190,7 +165,7 @@ function runPnpm(script: string, extra: string[] = []): boolean {
 }
 
 try {
-  await prepareRemovalFixture(fixtureRoot, copyTargets);
+  await prepareRemovalFixture(fixtureRoot);
   for (const excludedFixtureTest of [
     "tests/integration/security-followup-archive.test.ts",
     "tests/unit/ci-artifact-contract.test.ts",