Realign code with the 2026-07-31 findings-resolution rulings

The full bullet list from Implementation card bf080d9a — both ruling
batches, including the three appended mid-session by 16ef377:

- Restore subjects compose the inverse, never nest: crossing "Undo: S"
  emits "Redo: S" and vice versa; parity, not stack depth, reads a
  legacy double prefix (GitHistoryProvider.restoreSubject).
- Git-operation failures join the one-shot failure banner tier:
  BannerCenter.GitFailureBanner (undo/redo/branchSwitch/addGit), error
  tone at failure rank merged with write one-shots by recency; the
  postLoss compromise is retired at both AppModel wirings.
- order/schema optional below the board root: append-at-end reading
  (ordered siblings first, folder-name tie-break among the order-less),
  schema reads 1, both coerce-tier logged; the root keeps its
  requirements. Ranks.resolvedOrders materializes finite ranks so
  models and placement math stay untouched; first Writer rewrite
  stamps a real rank on touch, placement against an order-less sibling
  stamps that sibling inline in the same bracket. Agent guide v10
  teaches optional keys and zero-read filing. Hostile-YAML order
  shapes become coercion tests; Fixtures/Valid/optional-keys.kanban
  replaces the four retired Malformed boards.
- .gitignore is the relocation-heal noise gate: GitignoreRules pure
  matcher (standard semantics, board-root file only), loader consults
  it once per walk so matched loose files keep the stray posture;
  seeded (.DS_Store + .*.lanework-*) at board creation and template
  instantiation, healed in when missing at open — repo-nested
  included; empty file honored, existing files never edited; the
  committer's obedience via libgit2 status is pinned by test.
- Comments crash-residue sweep gates on step ownership: HistoryStep
  derives backing from its own undo expectations, backedContent unions
  both stacks, the sweep purges per-entry only what no live step owns.
- Skip-purge decoupled (16ef377): a stale-skipped coarse step strands
  whole in NativeHistoryProvider.strandedSteps — still backing, retired
  only at session end; clean exits purge as before.
- Coarse close step named "Changes to '<card>'"; the fine body-edit
  wording never leaks onto the board menu.
- Branch-switch settle clears every open card window's fine stack on
  Save All and Discard alike; the empty fold registers no coarse step.
- Close flush awaits its covering snapshot (quiesce + one generation
  bump, 1s bound), and an explicit flush now queues behind an
  in-flight one instead of skipping — the audit-caught interleaving
  could lose a close flush permanently when the debounce fired inside
  the close sequence; regression tests force both races.
- Commit comment bullets sort chronologically by created, not UUID.
- The production-unwired CardBodyEditSession.editSessionDidChange seam
  is deleted with its seam-only tests.
- Composition-root pins: beginSession composes the committer with the
  store's own EchoLedger and binds the announcer (the miswire class).
- Deliberate 06 conformance pass over every 2026-07-31-tagged
  sentence: fixed Change-custom-key subjects (the retired named
  generic was the only producer), the unbuilt Replace attachment
  vocabulary, heal commits now authored Lanework Integrity, the config
  reader scopes identity to plain [user] sections, add-git re-runs
  detection at create (a stale mode-none could initialize inside the
  user's repo), and add-git failures answer at the form or the banner.
  Structural residue filed on the Redesign board.

2554 tests / 439 suites green.

Claude-Session: https://claude.ai/code/session_01CqjXB7ASoWtbyoGod68k97

Fixtures/Valid/optional-keys.kanban/10000000-0000-4000-8000-000000000001/20000000-0000-4000-8000-000000000001/index.md

@@ -0,0 +1,8 @@
+---
+schema: 1
+kind: card
+order: 1024
+title: Ranked Card
+---
+The only card in this lane that says where it goes. Every sibling below reads as
+append-at-end, in folder-name order.

Fixtures/Valid/optional-keys.kanban/10000000-0000-4000-8000-000000000001/20000000-0000-4000-8000-000000000002/index.md

@@ -0,0 +1,6 @@
+---
+title: Minimum Agent Card
+---
+The whole legal minimum: one `mkdir` and one write, no `order` and no `schema`
+(08-agent-integration.md — "filing a card must need nothing but the schema").
+Reads as schema 1, at the bottom of the lane.

Fixtures/Valid/optional-keys.kanban/10000000-0000-4000-8000-000000000001/20000000-0000-4000-8000-000000000003/index.md

@@ -0,0 +1,8 @@
+---
+schema: 1
+kind: card
+order:
+title: Null Order Card
+---
+The hand-editor started the key and never gave it a value — reads as missing,
+which below the root is the append-at-end reading.

Fixtures/Valid/optional-keys.kanban/10000000-0000-4000-8000-000000000001/20000000-0000-4000-8000-000000000004/index.md

@@ -0,0 +1,8 @@
+---
+schema: 1
+kind: card
+order: banana
+title: Non-Numeric Order Card
+---
+Present but unusable — the same reading a missing key gets, recorded as a
+coercion with the text as written.

Fixtures/Valid/optional-keys.kanban/10000000-0000-4000-8000-000000000001/20000000-0000-4000-8000-000000000005/index.md

@@ -0,0 +1,9 @@
+---
+schema: 1
+kind: card
+order: .nan
+title: Non-Finite Order Card
+---
+NaN has no place in the total order the tie-break and midpoint math assume, so
+it is unusable exactly like `banana` — a coercion since 2026-07-31, not a
+rejection.

Fixtures/Valid/optional-keys.kanban/10000000-0000-4000-8000-000000000001/index.md

@@ -0,0 +1,6 @@
+---
+schema: 1
+kind: lane
+order: 1024
+title: Ranked Lane
+---