feat(brain): wire STREAM_BROWSER real-time modes into the reply engine (browser + Gemini)

Completes the two info modes in the Python brain:

- config.py: read STREAM_BROWSER / GEMINI_API_KEY / GEMINI_MODEL from env into
  Settings (stream_browser, gemini_api_key, gemini_model). Verified load_settings
  reads both modes.
- realtime_search.py: two fail-open backends returning the same fenced
  UNTRUSTED-WEB-EXTRACT envelope: browser_search() shells the Node CDP helper to
  drive the on-screen Chrome (visible on the broadcast); gemini_search() calls
  the Gemini REST API with google_search grounding.
- web_search.run(): routes by mode before the DDG cascade (true->browser,
  false->Gemini), falling through to DDG/Brave/Wikipedia on any miss.
- browse_and_play tool: plays a YouTube video on the shared screen (true mode
  only); registered in the tool registry.
- specs + docs/llm_contexts.md updated (new Gemini LLM context); CLAUDE.md spec
  registry updated.

Verified live against the running Chrome: true-mode webSearch returned real
Google results for "오늘 서울 날씨", browseAndPlay played the IU 밤편지 MV, and
false-mode degrades gracefully on a bad/absent key. A valid GEMINI_API_KEY is
still needed to confirm the real Gemini grounding output.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/jarvis/tools/builtin/web_search.py

@@ -594,6 +594,26 @@ class WebSearchTool(Tool):
             context.user_print(f"🌐 Searching the web for '{search_query}'…")
             debug_log(f"    🌐 searching for '{search_query}'", "web")
 
+            # Real-time info routing by STREAM_BROWSER (docs/stream_browser_modes.md):
+            # true  -> drive the on-screen Chrome (visible on the broadcast),
+            # false -> Gemini grounded search. Either falls through to the
+            # DDG/Brave/Wikipedia cascade below if it yields nothing (fail-open).
+            from .realtime_search import browser_search, gemini_search
+            if getattr(cfg, "stream_browser", True):
+                routed = browser_search(search_query)
+                if routed:
+                    debug_log("    🌐 routed via browser (STREAM_BROWSER=true)", "web")
+                    return ToolExecutionResult(success=True, reply_text=routed)
+            elif getattr(cfg, "gemini_api_key", ""):
+                routed = gemini_search(
+                    search_query,
+                    cfg.gemini_api_key,
+                    getattr(cfg, "gemini_model", "gemini-2.0-flash"),
+                )
+                if routed:
+                    debug_log("    🌐 routed via Gemini (STREAM_BROWSER=false)", "web")
+                    return ToolExecutionResult(success=True, reply_text=routed)
+
             # Overall wall-clock deadline across the full provider chain.
             # Individual providers have their own per-call timeouts, but
             # stacking DDG + Brave + Wikipedia worst-cases can otherwise