Drop CF_LOCAL_HOST; limit web-stack inference to containers (#163)

* config: Add local_host and web_stack options

Allow configuring local_host and web_stack in compose-farm.yaml instead
of requiring environment variables. This makes it easier to deploy the
web UI with just a config file mount.

- local_host: specifies which host is "local" for Glances connectivity
- web_stack: identifies the web UI stack for self-update detection

Environment variables (CF_LOCAL_HOST, CF_WEB_STACK) still work as
fallback for backwards compatibility.

Closes #152

* docs: Clarify glances_stack is used by CLI and web UI

* config: Env vars override config, add docs

- Change precedence: environment variables now override config values
  (follows 12-factor app pattern)
- Document all CF_* environment variables in configuration.md
- Update example-config.yaml to mention env var overrides

* config: Consolidate env vars, prefer config options

- Update docker-compose.yml to comment out CF_WEB_STACK and CF_LOCAL_HOST
  (now prefer setting in compose-farm.yaml)
- Update init-env to comment out CF_LOCAL_HOST (can be set in config)
- Update docker-deployment.md with new "Config option" column
- Simplify troubleshooting to prefer config over env vars

* config: Generate CF_LOCAL_HOST with config alternative note

Instead of commenting out CF_LOCAL_HOST, generate it normally but add
a note in the comment that it can also be set as 'local_host' in config.

* config: Extend local_host to all web UI operations

When running the web UI in a Docker container, is_local() can't detect
which host the container is on due to different network namespaces.

Previously local_host/CF_LOCAL_HOST only affected Glances connectivity.
Now it also affects:
- Container exec/shell (runs locally instead of via SSH)
- File editing (uses local filesystem instead of SSH)

Added is_local_host() helper that checks CF_LOCAL_HOST/config.local_host
first, then falls back to is_local() detection.

* refactor: DRY get_web_stack helper, add tests

- Move get_web_stack to deps.py to avoid duplication in streaming.py
  and actions.py
- Add tests for config.local_host and config.web_stack parsing
- Add tests for is_local_host, get_web_stack, and get_local_host helpers
- Tests verify env var precedence over config values

* glances: rely on CF_WEB_STACK for container mode

Restore docker-compose env defaults and document local_host scope.

* web: ignore local_host outside container

Document container-only behavior and adjust tests.

* web: infer local host from web_stack

Drop local_host config option and update docs/tests.

* Remove CF_LOCAL_HOST override

* refactor: move web_stack helpers to Config class

- Add get_web_stack() and get_local_host_from_web_stack() as Config methods
- Remove duplicate _get_local_host_from_web_stack() from glances.py and deps.py
- Update deps.py get_web_stack() to delegate to Config method
- Add comprehensive tests for the new Config methods

* config: remove web_stack config option

The web_stack config option was redundant since:
- In Docker, CF_WEB_STACK env var is always set
- Outside Docker, the container-specific behavior is disabled anyway

Simplify by only using the CF_WEB_STACK environment variable.

* refactor: remove get_web_stack wrapper from deps

Callers now use config.get_web_stack() directly instead of
going through a pointless wrapper function.

* prompts: add rule to identify pointless wrapper functions

.prompts/pr-review.md

@@ -6,6 +6,7 @@ Review the pull request for:
 - **Organization**: Is everything in the right place?
 - **Consistency**: Is it in the same style as other parts of the codebase?
 - **Simplicity**: Is it not over-engineered? Remember KISS and YAGNI. No dead code paths and NO defensive programming.
+- **No pointless wrappers**: Identify functions/methods that just call another function and return its result. Callers should call the underlying function directly instead of going through unnecessary indirection.
 - **User experience**: Does it provide a good user experience?
 - **PR**: Is the PR description and title clear and informative?
 - **Tests**: Are there tests, and do they cover the changes adequately? Are they testing something meaningful or are they just trivial?