feat(workspace): allow creation without an initial repository

Keep bootstrap, signing identity, config and resource-key allocation atomic with optional Repository intent. Preserve repository-present fingerprints for saved receipts; replay reads current authority at the initial key and never recreates missing assets.

Provide explicit repository-free CLI creation, optional TUI/Web creation inputs, nullable generated contracts, and valid empty catalog/Worker paths. Retain existing authenticated non-owner viewing policy pending the T-717 authorization decision.

Validation: root cargo check; server tests 639 lib + 11 bin; server-api 70 default / 77 typescript; client 52 lib + 2 integration; tui 337; yoi 11 lib + 120 bin. OpenAPI/TS freshness, cargo fmt and diff checks pass. Web check/build, 18 model tests, 268 component tests and Chromium 8 width/theme combinations pass; before/after visual evidence is documented in web/workspace/test/visual-review. Full Web suite has one independently reproduced baseline Ticket source-policy failure.

web/workspace/test/visual-review/README.md

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+# Optional initial repository validation (T-717 Web portion)
+
+These scenarios use the production static Workspace build and the existing
+`tools/web-ux` capture/process harness. The loopback proxy only extends the shared
+Home fixture's API responses for empty Worker lists and launch options; it does
+not replace the application shell, styles, or components. No real Workspace,
+account, repository, Runtime, or Worker is created.
+
+## Run
+
+From `web/workspace`, with the repository's pinned Chromium available:
+
+```sh
+deno task build
+deno task test:browser:empty-workspace
+```
+
+The browser test covers light/dark at 1440, 768, 390, and 320px: optional Git
+native validation, opting out after entering repository values, null creation
+response/navigation, zero-repository catalog reopening, normal embedded Worker
+submission without Workdir or Ticket assignment, and remote Runtime Workdir
+requirements. It uses dynamically allocated loopback ports and the existing
+owned-process cleanup harness. Screenshots and logs are ignored artifacts under
+`.svelte-kit/t717/browser`.
+
+From `tools/web-ux`:
+
+```sh
+deno task web-ux capture \
+  --scenario ../../web/workspace/test/visual-review/optional-repository.json \
+  --output ../../web/workspace/.svelte-kit/t717/visual --run-id empty-workspace
+
+deno task web-ux capture \
+  --scenario ../../web/workspace/test/visual-review/optional-repository-interactions.json \
+  --output ../../web/workspace/.svelte-kit/t717/visual --run-id creation-interactions
+```
+
+The interaction scenario intentionally rejects creation with HTTP400. Capture
+exit status 2 and the recorded request/console/visible validation errors are
+expected for `validation-error`, not evidence of a successful creation. No other
+capture error is expected. To repeat dark captures, use a scenario copy with
+`colorScheme: "dark"`, preserving the process cwd paths.
+
+## Implementer-owned visual review
+
+- Baseline revision: `e939cd4e4b1f6b63b81411fd7766062f2d69ad0d`.
+- Before: `.svelte-kit/t717/visual/before-final-light` and `before-dark`.
+  These use an isolated build under `.svelte-kit/t717/baseline-source`, with the
+  changed production form, catalog API, model, and CSS restored from baseline
+  Git source. The original pre-edit light capture is also retained as
+  `.svelte-kit/t717/visual/before-valid`.
+- After: `.svelte-kit/t717/visual/final-light`, `final-dark`,
+  `final-interactions-light`, and `final-interactions-dark`.
+- Comparisons: `.svelte-kit/t717/visual/final-comparison-light` and
+  `final-comparison-dark`.
+- Personas: synthetic owner and non-owner permission projections; catalog
+  creation/reopening uses the same synthetic account.
+- Viewports: 1440, 768, 390px; additional browser screenshots/checks at 320px.
+- Themes: light and dark.
+- States: zero repositories, empty Home/Sidebar, representative member work
+  records, long catalog names, unchecked/checked optional repository form,
+  populated inputs, and intentional Backend validation failure.
+- Reviewed by the implementer using `ViewImage`: before/after contact sheets,
+  individual narrow/mobile populated-form screenshots, and the final mobile
+  dark validation-error screenshot. Reviewed context bundles and accessibility
+  snapshots for document status, control names/state, screenshot hashes,
+  console/page/request errors, and capture points.
+- Fixed: catalog/form clipping at narrow content widths; repository field
+  disclosure/required-state handling. Chromium tests also found and fixed the
+  existing repository-key HTML pattern's invalid modern-regexp character class.
+- Result: pass. All baseline and final main captures have document status 200
+  and no retained browser/UI errors. Only the intentional HTTP400 interaction
+  errors remain. Home, member Sidebar, and Worker launch comparisons show zero
+  changed pixels; catalog changes are confined to the intended surface.
+
+## Validation and limitations
+
+- `deno task check`: 0 errors, 0 warnings.
+- Targeted model/catalog Deno tests: 18 passed.
+- `deno task test:component`: 29 files, 268 tests passed.
+- `deno task test:browser:empty-workspace`: passed (8 theme/width combinations).
+- `deno task build`: passed.
+- Web-scoped `git diff --check HEAD -- .`: passed.
+- `deno task test`: 522 passed, 1 pre-existing failure in
+  `src/lib/workspace/console/worker-console.ui.test.ts`,
+  “workspace Tickets surface provides Kanban and lifecycle controls”. It fails
+  the unchanged Ticket detail source assertion at line 429. The same failure
+  was reproduced against the isolated baseline source. Evidence:
+  `.svelte-kit/t717/unit.log` and `baseline-ticket-failure.log`.
+- Canonical OpenAPI and generated TypeScript were regenerated together.
+  The Web parser uses the generated nullable creation-response type directly.
+  Backend persistence/idempotency is covered separately by Store/catalog and
+  real HTTP boundary tests in `yoi-workspace-server`.
+