Right-panel Status tab rendered todo progress with coloured 6/8px dots
(bg-icon-success-base, bg-icon-info-base, bg-border-weak). DESIGN.md L201
forbids dots as state signals; the only sanctioned dot in PawWork is the
sidebar session-row unread orange dot.

This commit aligns the Status tab todo rendering with the canonical todo
widget already used in session-todo-dock.tsx and todowrite.tsx:

- completed → `<Icon name="circle-check">` 16x16
- pending / cancelled → `<Icon name="circle">` 16x16
- in_progress → 13x13 ring with brand-primary top border and pw-spin
- completed and cancelled rows uniformly get line-through + text-fg-weak
  (previously only cancelled was struck; cancelled was text-fg-weaker)
- gap-2.5 → gap-2 to match the dock spacing

Net: same Status tab, same todo data, marker style swapped to the visual
already shipping elsewhere in the app.

Refs #602 (Area B right-panel rewrite, slice 3)

Out of scope for this PR:
session-status-connections.tsx (servers / MCP / LSP / plugins) keeps its
dots for now; whether that section belongs in the right panel at all is
a separate product question (alert channel needed if it moves) and will
be tracked in a follow-up issue.

- Add packages/app/e2e/snap/status-summary-todos.snap.ts: opens the
  right panel after seeding todos in all four states (completed /
  in_progress / pending / cancelled) and screenshots the panel.
  Gives Slice 3 a durable visual baseline in addition to the
  todo-dock-restored target that already covers the marker shape.

- Address gemini-code-assist[bot] review on PR #861:
  - session-status-summary.test.ts: resolve source via
    new URL("…", import.meta.url) instead of __dirname + path.join,
    matching the repository test convention.
  - session-status-summary.tsx: add break-words to the todo content
    container so long todo strings wrap inside the narrow right panel,
    matching session-todo-dock.tsx text styling.

Refs #602, #861

Applies fixes flagged by the crosscheck round on PR #861:

- snap target: pass animations: "disabled" to panel.screenshot() so the
  in_progress 13×13 pw-spin ring captures the same orientation every
  run. Previously the screenshot froze whatever frame Playwright
  happened to land on, making the baseline non-deterministic across
  rebuilds (Codex P2).

- snap target: poll until at least four todo rows are visible before
  capturing, so a partial render does not silently produce a
  misleading baseline (Claude P3).

- unit test: assert literal 13px width/height on the spin ring so a
  size drift surfaces as a test failure instead of a passing comment
  (Codex P3).

Three places rendered the same 13×13 ring + circle/circle-check marker:

  packages/ui/src/components/message-part/tools/todowrite.tsx   (37 lines)
  packages/app/src/pages/session/composer/session-todo-dock.tsx (33 lines)
  packages/app/src/components/session/session-status-summary.tsx (37 lines, added by Slice 3)

Both rounds of crosscheck on PR #861 and a follow-up review flagged this
as a drift risk. Extract the marker once into packages/ui so any future
DESIGN.md change (ring size, palette, icon swap) propagates with a single
edit.

- New: packages/ui/src/components/todo-status-marker.tsx
  - status prop typed as TodoStatus | (string & {}) so the SDK's bare
    string status field (gen/types.gen.ts) flows through without casts.
  - Optional marginTop prop: dock + status-summary pass "1px" to align
    with body text baseline; todowrite leaves it unset (different row
    baseline).
- New: todo-status-marker.test.ts — source-text contract covering the
  status → icon mapping, 13×13 ring dimensions, --animate-pw-spin token,
  and conditional marginTop application.
- session-status-summary.test.ts: marker assertions moved out; only row
  behaviour (no leftover dot classes, strikethrough rule, delegation to
  the shared component) remains here.

Visual: byte-for-byte identical to the prior inline JSX at each callsite.
The new marker is a 1:1 lift of the existing pattern, not a rewrite, so
the existing snap baselines (status-summary-todos, todo-dock-restored)
both pass unchanged.

Refs #602, #861

Both Show branches now share a single 16x16 inline-flex wrapper that owns
the optional marginTop nudge. Previously the in_progress branch put the
nudge on its outer span, while the fallback Icon routed it through
splitProps onto the inner <svg> where the wrapper's align-items: center
erased it — so marginTop=1px only nudged in_progress rows, not the
pending/completed/cancelled ones. The shared wrapper makes the prop
behave symmetrically regardless of state.

Also drops the redundant 'color: var(--icon-base)' on the fallback Icon;
icon.css already applies the same colour to [data-component=icon].

Surfaced by crosscheck reviewer feedback on #861.

Spell out that marginTop is read once at render time and that callsites
pass a static literal — guards against a future reader assuming the
inline-style object will re-spread reactively when the prop changes.

Touch only the JSDoc comment; behaviour unchanged.