docs(cli[load]): Document new flags and config templating

why: New load flags and config templating need user-facing documentation.
what:
- Document --here, --no-shell-command-before, --debug flags
- Document config templating with --set KEY=VALUE

Author: tony

docs/cli/load.md

@@ -253,3 +253,57 @@ When progress is disabled, logging flows normally to the terminal and no spinner
 ### Before-script behavior
 
 During `before_script` execution, the progress bar shows a marching animation and a ⏸ status icon, indicating that tmuxp is waiting for the script to finish before continuing with pane creation.
+
+## Here mode
+
+The `--here` flag reuses the current tmux window instead of creating a new session. This is similar to teamocil's `--here` flag.
+
+```console
+$ tmuxp load --here .
+```
+
+When used, tmuxp builds the workspace panes inside the current window rather than spawning a new session.
+
+## Skipping shell_command_before
+
+The `--no-shell-command-before` flag skips all `shell_command_before` entries at every level (session, window, pane). This is useful for quick reloads when the setup commands (virtualenv activation, etc.) are already active.
+
+```console
+$ tmuxp load --no-shell-command-before myproject
+```
+
+## Debug mode
+
+The `--debug` flag shows tmux commands as they execute. This disables the progress spinner and attaches a debug handler to libtmux's logger, printing each tmux command to stderr.
+
+```console
+$ tmuxp load --debug myproject
+```
+
+## Config templating
+
+Workspace configs support Jinja2-style `{{ variable }}` placeholders. Pass values via `--set KEY=VALUE`:
+
+```console
+$ tmuxp load --set project=myapp mytemplate.yaml
+```
+
+Multiple variables can be passed:
+
+```console
+$ tmuxp load --set project=myapp --set env=staging mytemplate.yaml
+```
+
+In the config file, use double-brace syntax:
+
+```yaml
+session_name: "{{ project }}"
+windows:
+  - window_name: "{{ project }}-main"
+    panes:
+      - echo "Working on {{ project }}"
+```
+
+```{note}
+Values containing `{{ }}` must be quoted in YAML to avoid parse errors.
+```