test(plan): render task graph snapshots as mermaid markdown (#477)

## Motivation

Task graph plan snapshots are easier to review as Markdown diagrams than as generated JSONC. This PR replaces successful `task_graph.jsonc` snapshots with `task_graph.md` files that contain a compact Mermaid `flowchart TD` plus redacted task detail sections, while keeping query snapshot behavior unchanged.

Author: wan9chi

Cargo.lock

@@ -19,7 +19,6 @@ serde_json = { workspace = true }
 thiserror = { workspace = true }
 tracing = { workspace = true }
 vec1 = { workspace = true, features = ["serde"] }
-vite_graph_ser = { workspace = true }
 vite_path = { workspace = true }
 vite_str = { workspace = true }
 vite_workspace = { workspace = true }

crates/vite_task_graph/Cargo.toml

@@ -84,15 +84,6 @@ pub struct TaskNode {
     pub source: TaskSource,
 }
 
-impl vite_graph_ser::GetKey for TaskNode {
-    type Key<'a> = (&'a AbsolutePath, &'a str);
-
-    #[expect(clippy::disallowed_types, reason = "trait requires String as error type")]
-    fn key(&self) -> Result<Self::Key<'_>, String> {
-        Ok((&self.task_display.package_path, &self.task_display.task_name))
-    }
-}
-
 #[derive(Debug, thiserror::Error)]
 pub enum TaskGraphLoadError {
     #[error("Failed to load package graph")]

crates/vite_task_graph/src/lib.rs

@@ -0,0 +1,86 @@
+# task graph
+
+```mermaid
+flowchart TD
+  task_0["<workspace>/#env-test"]
+  task_1["<workspace>/#hello"]
+```
+
+## `<workspace>/#env-test`
+
+```json
+{
+  "task_display": {
+    "package_name": "additional-envs",
+    "task_name": "env-test",
+    "package_path": "<workspace>/"
+  },
+  "resolved_config": {
+    "commands": [
+      "TEST_VAR=hello_world vt tool print-env TEST_VAR"
+    ],
+    "resolved_options": {
+      "cwd": "<workspace>/",
+      "cache_config": {
+        "env_config": {
+          "fingerprinted_envs": [],
+          "untracked_env": [
+            "<default untracked envs>"
+          ]
+        },
+        "input_config": {
+          "includes_auto": true,
+          "positive_globs": [],
+          "negative_globs": []
+        },
+        "output_config": {
+          "includes_auto": true,
+          "positive_globs": [],
+          "negative_globs": []
+        }
+      }
+    }
+  },
+  "source": "PackageJsonScript"
+}
+```
+
+## `<workspace>/#hello`
+
+```json
+{
+  "task_display": {
+    "package_name": "additional-envs",
+    "task_name": "hello",
+    "package_path": "<workspace>/"
+  },
+  "resolved_config": {
+    "commands": [
+      "echo hello"
+    ],
+    "resolved_options": {
+      "cwd": "<workspace>/",
+      "cache_config": {
+        "env_config": {
+          "fingerprinted_envs": [],
+          "untracked_env": [
+            "<default untracked envs>"
+          ]
+        },
+        "input_config": {
+          "includes_auto": true,
+          "positive_globs": [],
+          "negative_globs": []
+        },
+        "output_config": {
+          "includes_auto": true,
+          "positive_globs": [],
+          "negative_globs": []
+        }
+      }
+    }
+  },
+  "source": "PackageJsonScript"
+}
+```
+