fix: add explicit workspace mode resolution for --config (#818)

README.md

@@ -249,8 +249,9 @@ Options:
         * <id(s)>: provide one or several ads by ID to update, like e.g. "--ads=1,2,3"
   --force           - alias for '--ads=all'
   --keep-old        - don't delete old ads on republication
-  --config=<PATH>   - path to the config YAML or JSON file (DEFAULT: ./config.yaml)
-  --logfile=<PATH>  - path to the logfile (DEFAULT: ./kleinanzeigen-bot.log)
+  --config=<PATH>   - path to the config YAML or JSON file (does not implicitly change workspace mode)
+  --workspace-mode=portable|xdg - overrides workspace mode for this run
+  --logfile=<PATH>  - path to the logfile (DEFAULT: depends on active workspace mode)
   --lang=en|de      - display language (STANDARD: system language if supported, otherwise English)
   -v, --verbose     - enables verbose output - only useful when troubleshooting issues
 ```
@@ -263,19 +264,31 @@ Limitation of `download`: It's only possible to extract the cheapest given shipp
 
 All configuration files can be in YAML or JSON format.
 
-### Installation modes (portable vs. system-wide)
+### Installation modes (portable vs. user directories)
 
 On first run, the app may ask which installation mode to use. In non-interactive environments (CI/headless), it defaults to portable mode and will not prompt.
 
-The `--config` and `--logfile` flags override only their specific paths. They do not change the chosen installation mode or other mode-dependent paths (downloads, state files, etc.).
+Path resolution rules:
+
+- Runtime files are mode-dependent write locations (for example, logfile, update state, browser profile/cache, diagnostics, and downloaded ads).
+- `--config` selects only the config file; it does not silently switch workspace mode.
+- `--workspace-mode=portable`: runtime files are rooted next to the active config file (or the current working directory if no `--config` is supplied).
+- `--workspace-mode=xdg`: runtime files use OS-standard user directories.
+- `--config` without `--workspace-mode`: mode is inferred from existing footprints; on ambiguity/unknown, the command fails with guidance (for example: `Could not infer workspace mode for --config ...`) and asks you to rerun with `--workspace-mode=portable` or `--workspace-mode=xdg`.
+
+Examples:
+
+- `kleinanzeigen-bot --config /sync/dropbox/config1.yaml verify` (no `--workspace-mode`): mode is inferred from detected footprints; if both portable and user-directories footprints are found (or none are found), the command fails and lists the found paths.
+- `kleinanzeigen-bot --workspace-mode=portable --config /sync/dropbox/config1.yaml verify`: runtime files are rooted at `/sync/dropbox/` (for example `/sync/dropbox/.temp/` and `/sync/dropbox/downloaded-ads/`).
+- `kleinanzeigen-bot --workspace-mode=xdg --config /sync/dropbox/config1.yaml verify`: config is read from `/sync/dropbox/config1.yaml`, while runtime files stay in user directories (for example Linux `~/.config/kleinanzeigen-bot/`, `~/.local/state/kleinanzeigen-bot/`, `~/.cache/kleinanzeigen-bot/`).
 
 1. **Portable mode (recommended for most users, especially on Windows):**
 
-   - Stores config, logs, downloads, and state in the current directory
+   - Stores config, logs, downloads, and state in the current working directory
    - No admin permissions required
    - Easy backup/migration; works from USB drives
 
-1. **System-wide mode (advanced users / multi-user setups):**
+1. **User directories mode (advanced users / multi-user setups):**
 
    - Stores files in OS-standard locations
    - Cleaner directory structure; better separation from working directory
@@ -283,9 +296,11 @@ The `--config` and `--logfile` flags override only their specific paths. They do
 
 **OS notes (brief):**
 
-- **Windows:** System-wide uses AppData (Roaming/Local); portable keeps everything beside the `.exe`.
-- **Linux:** System-wide follows XDG Base Directory spec; portable stays in the current working directory.
-- **macOS:** System-wide uses `~/Library/Application Support/kleinanzeigen-bot` (and related dirs); portable stays in the current directory.
+- **Windows:** User directories mode uses AppData (Roaming/Local); portable keeps everything beside the `.exe`.
+- **Linux:** User directories mode uses `~/.config/kleinanzeigen-bot/config.yaml`, `~/.local/state/kleinanzeigen-bot/`, and `~/.cache/kleinanzeigen-bot/`; portable uses `./config.yaml`, `./.temp/`, and `./downloaded-ads/`.
+- **macOS:** User directories mode uses `~/Library/Application Support/kleinanzeigen-bot/config.yaml` (config), `~/Library/Application Support/kleinanzeigen-bot/` (state/runtime), and `~/Library/Caches/kleinanzeigen-bot/` (cache/diagnostics); portable stays in the current working directory.
+
+If you have mixed legacy footprints (portable + XDG), pass an explicit mode (for example `--workspace-mode=portable`) and then clean up unused files. See [Configuration: Installation Modes](docs/CONFIGURATION.md#installation-modes).
 
 ### <a name="main-config"></a>1) Main configuration ⚙️