merge: integrate oss branch — budget gating, MCP back-channel, events, loopback-only bind

Key features from OSS branch:
- Budget gating: rolling per-provider spend caps with BUDGET_EXCEEDED task state
- Agent MCP back-channel: runners mint tokens; /mcp endpoint resolves them
- Chatbot MCP server at /chatbot/mcp (requires api_token in config)
- Event timeline: unified event stream replacing ad-hoc question/summary flows
- Loopback-only default bind (127.0.0.1:8484); external_bind_allowed=true to expose
- repository_url required on task creation (enforces traceability)
- Auto-checker: spawns verification task after each execution

Conflict resolutions:
- serve.go: keep cfg.Runners.XEnabled() conditional registration from main + agentRegistry from oss
- config.go: keep RunnersConfig from main + BudgetConfig/ExternalBindAllowed from oss
- server.go: handleStaticFiles (base-path rewrite) kept; deduplicated duplicate from both sides
- executor/claude.go: accepted oss deletion (ClaudeRunner replaced by ContainerRunner)
- container_test.go: added noopChannel + AgentChannel parameter to Run call

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/internal/config/bind_test.go b/internal/config/bind_test.go
new file mode 100644
index 0000000..8e0ab4b
--- /dev/null
+++ b/internal/config/bind_test.go
@@ -0,0 +1,27 @@
+package config
+
+import "testing"
+
+func TestValidateBindAddr(t *testing.T) {
+	cases := []struct {
+		addr     string
+		external bool
+		wantErr  bool
+	}{
+		{"127.0.0.1:8484", false, false}, // loopback ok
+		{"localhost:8484", false, false}, // loopback ok
+		{"[::1]:8484", false, false},     // ipv6 loopback ok
+		{":8484", false, true},           // all interfaces, not allowed
+		{"0.0.0.0:8484", false, true},    // all interfaces, not allowed
+		{"192.168.1.10:8484", false, true}, // LAN ip, not allowed
+		{":8484", true, false},           // all interfaces, explicitly allowed
+		{"0.0.0.0:8484", true, false},    // explicitly allowed
+		{"192.168.1.10:8484", true, false}, // explicitly allowed
+	}
+	for _, c := range cases {
+		err := ValidateBindAddr(c.addr, c.external)
+		if (err != nil) != c.wantErr {
+			t.Errorf("ValidateBindAddr(%q, external=%v): err=%v, wantErr=%v", c.addr, c.external, err, c.wantErr)
+		}
+	}
+}