Add context window, temperature, parallel requests, and sampling controls

New CLI flags (matching llama-server patterns):
  --ctx-size N       Context window / KV cache size (sliding window)
  --temp N           Default sampling temperature (default: 0.6)
  --top-p N          Top-p nucleus sampling (default: 1.0)
  --repeat-penalty N Repetition penalty factor
  --parallel N       Max concurrent request slots (default: 1)

Per-request overrides via JSON body:
  temperature, top_p, repetition_penalty, max_tokens

Concurrency control:
  AsyncSemaphore actor limits concurrent inference tasks

Also: commit Package.resolved for reproducible builds

Author: simba

.gitignore

@@ -1,7 +1,6 @@
 # Swift / SPM
 .build/
 .swiftpm/
-Package.resolved
 *.xcodeproj/
 *.xcworkspace/
 xcuserdata/