feat: add standalone WIP Text View signatures

Render one Object or paired Interface entity without path/context, lookups or wire-schema changes. Preserve declarations, summaries, optional/unit and empty distinctions; validate protocol semantics and bounded input before rendering. Add five spec/nested goldens and 13 external API tests plus a standalone doctest.

Validation: cargo fmt --all -- --check; cargo check --workspace --all-targets; cargo test --workspace --all-targets; cargo test --workspace --doc; nix develop -c bash (cargo clippy --workspace --all-targets -- -D warnings, RUSTDOCFLAGS='-D warnings' cargo doc --workspace --no-deps, cargo run --package wip-public-api-example); git diff --check. All passed. Default shell lacks clippy; declared Nix dev shell supplied it.

crates/wip-text-view/tests/golden/identifiers.txt

@@ -0,0 +1,8 @@
+interface "/::example" {
+  type `string` = {
+    `表示名`: string,
+  };
+  operation `find-item`(
+    `search term`: string,
+  ) -> `string`;
+}

crates/wip-text-view/tests/golden/issue-read.txt

@@ -0,0 +1,22 @@
+/// "Issueの内容と関連項目を読む。"
+interface "/::issue.read" {
+  type Relation = enum {
+    parent,
+    sibling,
+    related,
+  };
+  type RelatedItems = {
+    /// "同じWorldspace内の関連項目。"
+    items: [entry],
+    next_cursor?: string,
+  };
+  /// "本文を取得する。"
+  operation read_body() -> {
+    body: string,
+  };
+  /// "関係を指定して関連項目を取得する。"
+  operation get_related_items(
+    relation: Relation,
+    limit?: integer,
+  ) -> RelatedItems;
+}

crates/wip-text-view/tests/golden/nested.txt

@@ -0,0 +1,25 @@
+interface "/::example" {
+  /// "type summary"
+  type Z = {
+    /// "field summary"
+    z?: unit,
+    a: [union {
+      /// "case summary"
+      z,
+      /// ""
+      a(unit),
+      nested(enum {
+        /// "enum summary"
+        z,
+        a,
+      }),
+    }],
+  };
+  operation z(
+    z: unit,
+    a?: unit,
+  ) -> unit;
+  operation a()
+  /// "no params result"
+  -> unit;
+}

crates/wip-text-view/tests/golden/object.txt

@@ -0,0 +1,5 @@
+object {
+  name: "123";
+  description: "Issue 123の公開操作。本文はOperationで取得する。";
+  interfaces: ["/::issue.read", "/::issue.lifecycle"];
+}

crates/wip-text-view/tests/golden/union-return.txt

@@ -0,0 +1,18 @@
+interface "/::example" {
+  type CloseResult = union {
+    closed,
+    blocked({
+      dependencies: [entry],
+    }),
+  };
+  operation refresh() -> unit;
+  /// "対象を検索する。"
+  operation search(
+    /// "検索語。"
+    query: string,
+  )
+  /// "条件に一致する項目。"
+  -> {
+    items: [entry],
+  };
+}