feat: context window from model endpoints + percentage-based auto-compact

ModelInfo (kernel contract):
- Add contextWindow?: number field

OpenAI-stream listModels:
- Parse contextWindow from common field names (context_length,
  context_window, max_context_length, max_tokens)

Transport-contract:
- ModelsResponse: add optional modelInfo map (model name → { contextWindow? })
- Add ModelMetadata type
- Rename CompactThresholdResponse → CompactPercentResponse
- Rename SetCompactThresholdRequest → SetCompactPercentRequest

Credential store:
- Add getModelInfo(modelName) method — resolves full ModelInfo
  (including contextWindow) for a <credential>/<model> string

Transport-http:
- GET /models now includes modelInfo with contextWindow per model
- Rename compact-threshold endpoints → compact-percent

Session-orchestrator:
- Auto-compact now uses contextSize (not overcounted usage.inputTokens)
  compared against contextWindow * (percent / 100)
- Default percent: 85 (was flat 350000)
- resolveModelInfo dep added to look up contextWindow
- Passes modelName from the settled turn to the compaction service

Conversation store:
- Rename getCompactThreshold/setCompactThreshold → getCompactPercent/setCompactPercent
- compactThresholdKey → compact-percent key

1 files changed, 2 insertions, 2 deletions

diff --git a/packages/session-orchestrator/src/queue.test.ts b/packages/session-orchestrator/src/queue.test.ts
index 346f9c4..58de4a9 100644
--- a/packages/session-orchestrator/src/queue.test.ts
+++ b/packages/session-orchestrator/src/queue.test.ts
@@ -87,10 +87,10 @@ function createInMemoryStore(): ConversationStore & {
 		},
 		async setConversationStatus() {},
 		async replaceHistory() {},
-		async getCompactThreshold() {
+		async getCompactPercent() {
 			return null;
 		},
-		async setCompactThreshold() {},
+		async setCompactPercent() {},
 		async forkHistory() {},
 		async setCompactedFrom() {},
 	};