feat(web): add Parallel as alternative web search/extract backend (#1696)

* feat(web): add Parallel as alternative web search/extract backend

Adds Parallel (parallel.ai) as a drop-in alternative to Firecrawl for
web_search and web_extract tools using the official parallel-web SDK.

- Backend selection via WEB_SEARCH_BACKEND env var (auto/parallel/firecrawl)
- Auto mode prefers Firecrawl when both keys present; Parallel when sole backend
- web_crawl remains Firecrawl-only with clear error when unavailable
- Lazy SDK imports, interrupt support, singleton clients
- 16 new unit tests for backend selection and client config

Co-authored-by: s-jag <s-jag@users.noreply.github.com>

* fix: add PARALLEL_API_KEY to config registry and fix web_crawl policy tests

Follow-up for Parallel backend integration:
- Add PARALLEL_API_KEY to OPTIONAL_ENV_VARS (hermes doctor, env blocklist)
- Add to set_config_value api_keys list (hermes config set)
- Add to doctor keys display
- Fix 2 web_crawl policy tests that didn't set FIRECRAWL_API_KEY
  (needed now that web_crawl has a Firecrawl availability guard)

* refactor: explicit backend selection via hermes tools, not auto-detect

Replace the auto-detect backend selection with explicit user choice:
- hermes tools saves WEB_SEARCH_BACKEND to .env when user picks a provider
- _get_backend() reads the explicit choice first
- Fallback only for manual/legacy config (uses whichever key is present)
- _is_provider_active() shows [active] for the selected web backend
- Updated tests, docs, and .env.example to remove 'auto' mode language

* refactor: use config.yaml for web backend, not env var

Match the TTS/browser pattern — web.backend is stored in config.yaml
(set by hermes tools), not as a WEB_SEARCH_BACKEND env var.

- _load_web_config() reads web: section from config.yaml
- _get_backend() reads web.backend from config, falls back to key detection
- _configure_provider() saves to config dict (saved to config.yaml)
- _is_provider_active() reads from config dict
- Removed WEB_SEARCH_BACKEND from .env.example, set_config_value, docs
- Updated all tests to mock _load_web_config instead of env vars

---------

Co-authored-by: s-jag <s-jag@users.noreply.github.com>

hermes_cli/config.py

@@ -550,6 +550,14 @@ OPTIONAL_ENV_VARS = {
     },
 
     # ── Tool API keys ──
+    "PARALLEL_API_KEY": {
+        "description": "Parallel API key for AI-native web search and extract",
+        "prompt": "Parallel API key",
+        "url": "https://parallel.ai/",
+        "tools": ["web_search", "web_extract"],
+        "password": True,
+        "category": "tool",
+    },
     "FIRECRAWL_API_KEY": {
         "description": "Firecrawl API key for web search and scraping",
         "prompt": "Firecrawl API key",
@@ -1506,6 +1514,7 @@ def show_config():
     keys = [
         ("OPENROUTER_API_KEY", "OpenRouter"),
         ("VOICE_TOOLS_OPENAI_KEY", "OpenAI (STT/TTS)"),
+        ("PARALLEL_API_KEY", "Parallel"),
         ("FIRECRAWL_API_KEY", "Firecrawl"),
         ("BROWSERBASE_API_KEY", "Browserbase"),
         ("BROWSER_USE_API_KEY", "Browser Use"),
@@ -1655,7 +1664,7 @@ def set_config_value(key: str, value: str):
     # Check if it's an API key (goes to .env)
     api_keys = [
         'OPENROUTER_API_KEY', 'OPENAI_API_KEY', 'ANTHROPIC_API_KEY', 'VOICE_TOOLS_OPENAI_KEY',
-        'FIRECRAWL_API_KEY', 'FIRECRAWL_API_URL', 'BROWSERBASE_API_KEY', 'BROWSERBASE_PROJECT_ID', 'BROWSER_USE_API_KEY',
+        'PARALLEL_API_KEY', 'FIRECRAWL_API_KEY', 'FIRECRAWL_API_URL', 'BROWSERBASE_API_KEY', 'BROWSERBASE_PROJECT_ID', 'BROWSER_USE_API_KEY',
         'FAL_KEY', 'TELEGRAM_BOT_TOKEN', 'DISCORD_BOT_TOKEN',
         'TERMINAL_SSH_HOST', 'TERMINAL_SSH_USER', 'TERMINAL_SSH_KEY',
         'SUDO_PASSWORD', 'SLACK_BOT_TOKEN', 'SLACK_APP_TOKEN',