T08 iter 2: Reveal, Resolve, End; relations and the DARVO trigger

Round machinery, system-driven (GR-R04/R06/R08):

- GR-R06 fixed step order with GR-R07 Lead-first ordering inside a step.
  Steps 1 (GROUND), 3 (DARVO stages), 4 (INVESTIGATE) and 6 (SOLVE) are
  not implemented yet; their Actions resolve as no-ops and no scenario
  claims coverage of them.
- SUPPORT GR-A03/A04/A05 and ATTACK GR-A06..A09, with relation
  formation, flip and break per GR-L01/L03/L04 and Protection
  cancellation.
- GR-R08 End: DARVO trigger at Stress 5 in Lead order, Lead rotation,
  Round advance, per-round flags cleared.
- Stress clamps 0-5 on every application, the U2 default, so a mid-round
  spike that is reduced before End does not trigger DARVO.

Two consent-dependent rules are deliberately left out because they need
a decision command rather than a default: Bond formation (GR-L02) and
the target's flip-or-break choice on Support-through-Rivalry (GR-A05).
Both are noted in code and covered by a provisional scenario.

Fixes a defect in the T07 scaffold: relations were keyed by a tuple,
which JSON cannot use as an object key, so state_hash would have
panicked on any state holding a relation. Relation keys are now a Pair
newtype serialized as "a-b", with a regression test.

setup.patch may now create a final key so scenarios can seed open-ended
maps; a typo anywhere earlier in the path is still an error.

8 scenarios pass, 28 rules covered; 17 tests, fmt/clippy green.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scenarios/ground/gr-a04-bond-support.yaml

@@ -0,0 +1,48 @@
+scenario: ground/gr-a04-bond-support
+description: >
+  Support through an existing Bond: −2 Stress and the target's Freedom
+  token is readied (GR-A04, GR-F04). A Support with no relation forms no
+  Bond, because GR-L02 requires the target's consent.
+covers: [GR-A04, GR-F04, GR-L02, GR-L05]
+provisional: true
+seed: 42
+setup:
+  players: 3
+  preset: standard-3p
+  patch:
+    "lead": 0
+    "relations.0-1": Bond
+    "players.1.stress": 3
+    "players.1.freedom_ready": false
+commands:
+  - actor: P1
+    cmd: select_action
+    args: { action: SUPPORT, target: P2 }
+  # No relation with P3: Stress drops but no Bond forms without consent.
+  - actor: P2
+    cmd: select_action
+    args: { action: SUPPORT, target: P3 }
+  - actor: P3
+    cmd: select_action
+    args: { action: GROUND }
+  - actor: SYSTEM
+    cmd: reveal
+  - actor: SYSTEM
+    cmd: resolve
+expect:
+  events:
+    - kind: StressSet
+      player: 1
+      stress: 1
+    - kind: FreedomReadied
+      player: 1
+    - kind: StressSet
+      player: 2
+      stress: 1
+  state:
+    "players.1.stress": 1
+    "players.1.freedom_ready": true
+    "players.2.stress": 1
+    # No Bond formed with P3: the relation map is unchanged.
+    "relations": { "0-1": Bond }
+  rejects: []