Deepen Copilot proposal realization

[delebedev]

Realize Copilot metadata and native responses in one atomic pass so the two representations cannot drift.

Require acceptance stack resolution to observe a post-action horizon before treating empty-stack priority as settled.

Serialize harness phase advancement with client submission and make the keep-priority proof deterministic.

Refs #leyline-zq222.1

Refs #leyline-fbct6

[github-actions]

Test Results

 1 774 files  ±0  1 774 suites  ±0   5m 32s ⏱️ + 1m 48s
 2 937 tests ±0  2 935 ✅ ±0      2 💤 ±0  0 ❌ ±0 
10 679 runs  ±0  2 947 ✅ ±0  7 732 💤 ±0  0 ❌ ±0 

Results for commit f7a16cc. ± Comparison against base commit 1e20a5e.

This pull request removes 52 and adds 52 tests. Note that renamed tests count towards both.

leyline.acceptance.MatchdoorAcceptanceExecutorPolicyTest ‑ an empty stack at client priority needs no further pass
leyline.copilot.ProposalTranslatorTest ‑ Adventure cast action → cast_adventure intent
leyline.copilot.ProposalTranslatorTest ‑ activate action → activate intent with ability grpId
leyline.copilot.ProposalTranslatorTest ‑ alt-cost cast action → cast_mdfc intent carrying the alternative grpId
leyline.copilot.ProposalTranslatorTest ‑ base cast action → cast intent, no alternative
leyline.copilot.ProposalTranslatorTest ‑ cancel action → cancel intent (a realizable back-out, not unrealizable)
leyline.copilot.ProposalTranslatorTest ‑ casting-time X retains ctoId and numeric value
leyline.copilot.ProposalTranslatorTest ‑ declare-all-attackers → attack_all intent
leyline.copilot.ProposalTranslatorTest ‑ declare-attackers → attack intent with resolved attackers
leyline.copilot.ProposalTranslatorTest ‑ declare-blockers → block intent with blocker→attacker pairs
…

leyline.acceptance.MatchdoorAcceptanceExecutorPolicyTest ‑ a published post-action priority horizon needs no further pass
leyline.acceptance.MatchdoorAcceptanceExecutorPolicyTest ‑ a stale priority horizon still advances an empty stack once
leyline.copilot.CopilotProposalRealizerResponseTest ‑ assign damage echoes each attacker's (target, damage) pairs
leyline.copilot.CopilotProposalRealizerResponseTest ‑ auto-tap payment confirms the offered solution by index
leyline.copilot.CopilotProposalRealizerResponseTest ‑ cancel action is a lone CancelActionReq tagged to the prompt
leyline.copilot.CopilotProposalRealizerResponseTest ‑ casting-time X serializes inside the casting option response
leyline.copilot.CopilotProposalRealizerResponseTest ‑ declare attackers selection names the opponent as damage recipient
leyline.copilot.CopilotProposalRealizerResponseTest ‑ declare blockers is a lone assignment toggle answering the prompt
leyline.copilot.CopilotProposalRealizerResponseTest ‑ declare no blockers submits an empty selection against the current prompt
leyline.copilot.CopilotProposalRealizerResponseTest ‑ distribution serializes each target amount against the prompt
…

♻️ This comment has been updated with latest results.

[github-actions]

CI Report — Gate

Tests: 2947/2947 passed (7732 skipped)

Coverage: 80.0% (31443/39313 lines)

Module	Coverage	Lines
domain	🟡 71%	340/482
engine (gate)	🟡 78%	27232/35078
engine	🟡 80%	27969/35078
web	🟢 83%	1194/1434
native	🟢 84%	1940/2319

Slow tests (>3s): 12

• ChannelPuzzleTest.Twinshot Sniper channel from hand kills opponent (12.8s)
• AcceptanceSuitesTest.ai-green-controls — firebending-bolt-lethal (7.9s)
• SnapshotShadowProbeTest.stack-independent action picks hydrate faithfully (AAR match, no mismatch) (6.3s)
• CopilotProposalServiceTest.proposes play_land for the opening land-drop AAR against a live game (6.3s)
• NativeMatchDoorBootstrapTest.native match bootstrap binds an active TCP channel (5.8s)
• BrawlMatchFlowTest.brawl game starts with correct life, hand, and commander in command zone (5.1s)
• BrawlMatchFlowTest.commander recast offer includes commander tax (4.8s)
• PureDiffReplayTest.one-turn scripted scenario replays byte-identically (4.3s)
• ValueProjectionBoundaryTest.only the named projection shells materialize ability exhaustion facts (4.1s)
• AiTurnConformanceTest.AI action diffs contain ZoneTransfer annotations (local AI visibility) (3.9s)
• AcceptanceSuitesTest.mechanics-protocol — saga-tribute-transform (3.9s)
• AcceptanceSuitesTest.mechanics-protocol — power-up-serpent-specialist (3.5s)