feat: add repo_update control modes

docs/configuration-reference.md

@@ -23,6 +23,22 @@ Here is a breakdown of all configuration options:
   - Enable or disable checking for updates before running operations.
   - Default: `false`.
 
+- **`repo_update`** (Object)
+  - Controls how repository index updates (e.g. `apt update`, `brew update`) are handled per
+    installer type. Keys are installer types, values are one of:
+    - `once` — Run the repo update at most once per sofmani run (default).
+    - `always` — Run the repo update before every install/update operation.
+    - `never` — Skip the repo update entirely.
+  - Supported types: `brew`, `apt`, `apk`.
+  - Default: `once` for all supported types.
+  - Example:
+    ```yaml
+    repo_update:
+      brew: once
+      apt: always
+      apk: never
+    ```
+
 - **`summary`** (Boolean)
   - Enable or disable the installation summary at the end.
   - The summary shows newly installed and upgraded software in a hierarchical format.
@@ -73,6 +89,9 @@ debug: false
 check_updates: true
 summary: true
 category_display: border
+repo_update:
+  brew: once
+  apt: once
 defaults:
   type:
     brew:

docs/installer-configuration.md

@@ -493,6 +493,9 @@ install:
 
 - **`brew`**
   - **Description**: Installs packages using Homebrew.
+  - **Repo update**: Brew auto-updates its index on each command. By default, sofmani lets the first
+    brew command auto-update normally and suppresses it for subsequent ones (`once` mode). Configure
+    via the top-level [`repo_update`](./configuration-reference.md#global-options) option.
 
   - **Options**:
     - `opts.tap`: Name of the tap to install the package from.
@@ -513,6 +516,9 @@ install:
 - **`apt`/`apk`**
   - **Description**: Installs packages using apt install or apt add.
     - Use `type: apt` for `apt install`, and `type: apk` for `apk add`.
+  - **Repo update**: Runs `apt update` or `apk update` before installing. By default, the update
+    runs at most once per sofmani run (`once` mode). Configure via the top-level
+    [`repo_update`](./configuration-reference.md#global-options) option.
   - **Options**:
     - `opts.flags`: Additional flags to pass to commands (fallback for install/update).
     - `opts.install_flags`: Additional flags to pass only during install.