docs: fix script name in directory tree examples (#2555)

* docs: fix script name in directory tree examples

Replace update-claude-md.sh with the actual filename setup-tasks.sh
in two directory tree examples (Steps 2 and 4 of the detailed walkthrough).

* docs: fix .specify/scripts layout to show bash/ and powershell/ subdirs

install_shared_infra() installs scripts under .specify/scripts/bash/
(script_type="sh") or .specify/scripts/powershell/ (script_type="ps"),
not directly under .specify/scripts/. Update docs/installation.md and
the _install_shared_infra docstring to reflect the actual on-disk layout.

* docs: update README tree examples to show scripts/bash/ subdirectory

Scripts are installed under .specify/scripts/bash/ (or powershell/)
not directly under .specify/scripts/. Fix both tree diagrams in the
Detailed Process walkthrough to match the actual on-disk layout.

README.md

@@ -404,11 +404,12 @@ At this stage, your project folder contents should resemble the following:
     ├── memory
     │  └── constitution.md
     ├── scripts
-    │  ├── check-prerequisites.sh
-    │  ├── common.sh
-    │  ├── create-new-feature.sh
-    │  ├── setup-plan.sh
-    │  └── update-claude-md.sh
+    │  └── bash
+    │      ├── check-prerequisites.sh
+    │      ├── common.sh
+    │      ├── create-new-feature.sh
+    │      ├── setup-plan.sh
+    │      └── setup-tasks.sh
     ├── specs
     │  └── 001-create-taskify
     │      └── spec.md
@@ -465,11 +466,12 @@ The output of this step will include a number of implementation detail documents
 ├── memory
 │  └── constitution.md
 ├── scripts
-│  ├── check-prerequisites.sh
-│  ├── common.sh
-│  ├── create-new-feature.sh
-│  ├── setup-plan.sh
-│  └── update-claude-md.sh
+│  └── bash
+│      ├── check-prerequisites.sh
+│      ├── common.sh
+│      ├── create-new-feature.sh
+│      ├── setup-plan.sh
+│      └── setup-tasks.sh
 ├── specs
 │  └── 001-create-taskify
 │      ├── contracts

docs/installation.md

@@ -94,7 +94,10 @@ After initialization, you should see the following commands available in your co
 - `/speckit.plan` - Generate implementation plans  
 - `/speckit.tasks` - Break down into actionable tasks
 
-The `.specify/scripts` directory will contain both `.sh` and `.ps1` scripts.
+Scripts are installed into a variant subdirectory matching the chosen script type:
+
+- `.specify/scripts/bash/` — contains `.sh` scripts (default on Linux/macOS)
+- `.specify/scripts/powershell/` — contains `.ps1` scripts (default on Windows)
 
 ## Troubleshooting
 

src/specify_cli/__init__.py

@@ -229,9 +229,10 @@ def _install_shared_infra(
 ) -> bool:
     """Install shared infrastructure files into *project_path*.
 
-    Copies ``.specify/scripts/`` and ``.specify/templates/`` from the
-    bundled core_pack or source checkout.  Tracks all installed files
-    in ``speckit.manifest.json``.
+    Copies ``.specify/scripts/<variant>/`` and ``.specify/templates/`` from
+    the bundled core_pack or source checkout, where ``<variant>`` is
+    ``bash`` when *script_type* is ``"sh"`` and ``powershell`` when it is
+    ``"ps"``.  Tracks all installed files in ``speckit.manifest.json``.
 
     Page templates are processed to resolve ``__SPECKIT_COMMAND_<NAME>__``
     placeholders using *invoke_separator* (``"."`` for markdown agents,