help: update CLI help for Hugging Face and effort options

Document the new Hugging Face provider, HF_TOKEN auto-detection,
and the --effort option.

src/help.zon

@@ -131,6 +131,7 @@
     \\Examples:
     \\  {0s} agent                                (auto-detects API key from env)
     \\  {0s} agent --provider anthropic --model claude-sonnet-4-6
+    \\  {0s} agent --provider huggingface         (HF serverless router, HF_TOKEN)
     \\  {0s} agent --provider ollama --model qwen3.5:latest
     \\  {0s} agent --no-llm                       (basic slash-command-only REPL)
     \\  {0s} agent script.js                      (run a saved script, then exit)
@@ -149,7 +150,8 @@
     \\--provider <PROVIDER>      The AI provider.
     \\                           When omitted, lightpanda auto-detects an API key
     \\                           from your environment (ANTHROPIC_API_KEY,
-    \\                           OPENAI_API_KEY, GOOGLE_API_KEY/GEMINI_API_KEY).
+    \\                           OPENAI_API_KEY, GOOGLE_API_KEY/GEMINI_API_KEY,
+    \\                           HF_TOKEN).
     \\                           With exactly one key set: that provider is used.
     \\                           With multiple keys on a TTY: you'll be prompted
     \\                           to pick; in non-interactive contexts, pass
@@ -158,8 +160,12 @@
     \\                           natural-language input, no LOGIN /
     \\                           ACCEPT_COOKIES keywords).
     \\
+    \\                           ollama is never auto-detected (it needs no key);
+    \\                           select it explicitly with --provider ollama.
+    \\
     \\                           Allowed values:
-    \\                             "anthropic", "openai", "gemini", "ollama".
+    \\                             "anthropic", "openai", "gemini",
+    \\                             "huggingface", "ollama".
     \\                           In the REPL, use /provider to list and change
     \\                           providers.
     \\
@@ -177,6 +183,9 @@
     \\--base-url <URL>           Override the API base URL for the provider.
     \\                           Defaults to the provider's standard endpoint.
     \\                           Ollama default: http://localhost:11434/v1.
+    \\                           Hugging Face default is the serverless router
+    \\                           (https://router.huggingface.co/v1); point this
+    \\                           at a dedicated Inference Endpoint to use one.
     \\
     \\--system-prompt <STRING>   Override the default system prompt.
     \\
@@ -208,8 +217,21 @@
     \\                             high    + the matching `[result: ...]` body
     \\                                     (required by the benchmarks harness).
     \\
+    \\--effort <LEVEL>           Per-turn reasoning budget, mapped to each
+    \\                           provider's native thinking/reasoning knob.
+    \\                           Default: low in the REPL (snappy turns),
+    \\                           medium in one-shot --task mode. In the REPL,
+    \\                           use /effort to change it.
+    \\
+    \\                           Allowed values:
+    \\                             none, minimal, low, medium, high, xhigh.
+    \\
+    \\The provider, model, effort, and verbosity you choose in the REPL are
+    \\remembered per-directory in .lp-agent.zon and reused on the next run.
+    \\
     \\API keys are read from the environment: ANTHROPIC_API_KEY, OPENAI_API_KEY,
-    \\or GOOGLE_API_KEY/GEMINI_API_KEY. Ollama does not require an API key.
+    \\GOOGLE_API_KEY/GEMINI_API_KEY, or HF_TOKEN. Ollama does not require an API
+    \\key.
     ,
     .version =
     \\usage:  {0s} version