Iter 2: verschachteltes if, Strings, JSON-Output, deps

- Codegen: current_block-Tracking ersetzt die Heuristik im phi-Lowering;
  verschachtelte if-Ausdrücke produzieren jetzt korrekte LLVM IR.
  examples/max3.ail.json + Test schützt gegen Regression.
- Strings: Lit::Str / Type Str / io/print_str Effekt-Op; Strings sind im
  MVP immutable Konstanten. examples/hello.ail.json als zweiter E2E-Test.
- CLI: --json für manifest und builtins; neuer deps-Subcommand listet
  statische Symbol-Referenzen pro Definition. Effekt-Ops mit Prefix
  effect: markiert.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

examples/hello.ail.json

@@ -0,0 +1,25 @@
+{
+  "schema": "ailang/v0",
+  "name": "hello",
+  "imports": [],
+  "defs": [
+    {
+      "kind": "fn",
+      "name": "main",
+      "type": {
+        "k": "fn",
+        "params": [],
+        "ret": { "k": "con", "name": "Unit" },
+        "effects": ["IO"]
+      },
+      "params": [],
+      "body": {
+        "t": "do",
+        "op": "io/print_str",
+        "args": [
+          { "t": "lit", "lit": { "kind": "str", "value": "Hallo, AILang." } }
+        ]
+      }
+    }
+  ]
+}

examples/max3.ail.json

@@ -0,0 +1,113 @@
+{
+  "schema": "ailang/v0",
+  "name": "max3",
+  "imports": [],
+  "defs": [
+    {
+      "kind": "fn",
+      "name": "max",
+      "type": {
+        "k": "fn",
+        "params": [
+          { "k": "con", "name": "Int" },
+          { "k": "con", "name": "Int" }
+        ],
+        "ret": { "k": "con", "name": "Int" },
+        "effects": []
+      },
+      "params": ["a", "b"],
+      "body": {
+        "t": "if",
+        "cond": {
+          "t": "app",
+          "fn": { "t": "var", "name": ">" },
+          "args": [
+            { "t": "var", "name": "a" },
+            { "t": "var", "name": "b" }
+          ]
+        },
+        "then": { "t": "var", "name": "a" },
+        "else": { "t": "var", "name": "b" }
+      }
+    },
+    {
+      "kind": "fn",
+      "name": "max3",
+      "type": {
+        "k": "fn",
+        "params": [
+          { "k": "con", "name": "Int" },
+          { "k": "con", "name": "Int" },
+          { "k": "con", "name": "Int" }
+        ],
+        "ret": { "k": "con", "name": "Int" },
+        "effects": []
+      },
+      "params": ["a", "b", "c"],
+      "doc": "Demonstriert verschachteltes if (statt max-call) zum Test des Block-Trackings.",
+      "body": {
+        "t": "if",
+        "cond": {
+          "t": "app",
+          "fn": { "t": "var", "name": ">" },
+          "args": [
+            { "t": "var", "name": "a" },
+            { "t": "var", "name": "b" }
+          ]
+        },
+        "then": {
+          "t": "if",
+          "cond": {
+            "t": "app",
+            "fn": { "t": "var", "name": ">" },
+            "args": [
+              { "t": "var", "name": "a" },
+              { "t": "var", "name": "c" }
+            ]
+          },
+          "then": { "t": "var", "name": "a" },
+          "else": { "t": "var", "name": "c" }
+        },
+        "else": {
+          "t": "if",
+          "cond": {
+            "t": "app",
+            "fn": { "t": "var", "name": ">" },
+            "args": [
+              { "t": "var", "name": "b" },
+              { "t": "var", "name": "c" }
+            ]
+          },
+          "then": { "t": "var", "name": "b" },
+          "else": { "t": "var", "name": "c" }
+        }
+      }
+    },
+    {
+      "kind": "fn",
+      "name": "main",
+      "type": {
+        "k": "fn",
+        "params": [],
+        "ret": { "k": "con", "name": "Unit" },
+        "effects": ["IO"]
+      },
+      "params": [],
+      "body": {
+        "t": "do",
+        "op": "io/print_int",
+        "args": [
+          {
+            "t": "app",
+            "fn": { "t": "var", "name": "max3" },
+            "args": [
+              { "t": "lit", "lit": { "kind": "int", "value": 3 } },
+              { "t": "lit", "lit": { "kind": "int", "value": 17 } },
+              { "t": "lit", "lit": { "kind": "int", "value": 9 } }
+            ]
+          }
+        ]
+      }
+    }
+  ]
+}