Evaluator: real agent runtime + Session type checking (L9)

Evaluator (major upgrade from stubs to working runtime):
- Loop: real iteration with break/continue/return signals, 10K safety limit
- Spawn: creates AgentInstance with handlers, state, inbox from registered decls
- Send/SendFinal: delivers messages to target agent's inbox via Handle
- Receive: pops from current agent's inbox (non-blocking)
- Exchange: send + synchronous handler execution + reply collection
- Method calls: String (length/to_upper/to_lower), List (length/get/push),
  Record (keys), Handle (id)
- Agent handler execution: run_agent_handler() dispatches to matching handler
- register_agents(program) pre-registers AgentDecls for spawn lookup
- Break/Continue AST variants added to ControlStmt

Type checker — Session types (Kategoria L9):
- ProtocolTypeInfo: registered during Pass 1 with extracted roles
- project_protocol(): global protocol → local view per role
  (Message steps become Send/Receive based on sender/receiver matching)
- check_agent_protocol_compliance(): agents declaring `implements Protocol.Role`
  verified to have handlers for all projected Receive steps
- SessionProtocolViolation error kind for missing handlers
- LocalStep enum: Send, Receive, Branch, Loop, Rec

Tests: 160 total (was 141) — 15 new eval tests + 4 new session type tests

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

crates/oo7-core/src/ast.rs

@@ -130,6 +130,10 @@ pub enum ControlStmt {
     },
     /// `return [expr]`
     Return(Option<ControlExpr>),
+    /// `break [expr]` — exit the enclosing loop, optionally with a value
+    Break(Option<ControlExpr>),
+    /// `continue` — skip to the next iteration of the enclosing loop
+    Continue,
     /// `reversible { ... }` — marks a block as reversible
     Reversible(Vec<ControlStmt>),
     /// `irreversible { ... }` — marks a block as irreversible