feat(stt): add free local whisper transcription via faster-whisper (#1185)

* fix: Home Assistant event filtering now closed by default

Previously, when no watch_domains or watch_entities were configured,
ALL state_changed events passed through to the agent, causing users
to be flooded with notifications for every HA entity change.

Now events are dropped by default unless the user explicitly configures:
- watch_domains: list of domains to monitor (e.g. climate, light)
- watch_entities: list of specific entity IDs to monitor
- watch_all: true (new option — opt-in to receive all events)

A warning is logged at connect time if no filters are configured,
guiding users to set up their HA platform config.

All 49 gateway HA tests + 52 HA tool tests pass.

* docs: update Home Assistant integration documentation

- homeassistant.md: Fix event filtering docs to reflect closed-by-default
  behavior. Add watch_all option. Replace Python dict config example with
  YAML. Fix defaults table (was incorrectly showing 'all'). Add required
  configuration warning admonition.
- environment-variables.md: Add HASS_TOKEN and HASS_URL to Messaging section.
- messaging/index.md: Add Home Assistant to description, architecture
  diagram, platform toolsets table, and Next Steps links.

* fix(terminal): strip provider env vars from background and PTY subprocesses

Extends the env var blocklist from #1157 to also cover the two remaining
leaky paths in process_registry.py:

- spawn_local() PTY path (line 156)
- spawn_local() background Popen path (line 197)

Both were still using raw os.environ, leaking provider vars to background
processes and interactive PTY sessions. Now uses the same dynamic
_HERMES_PROVIDER_ENV_BLOCKLIST from local.py.

Explicit env_vars passed to spawn_local() still override the blocklist,
matching the existing behavior for callers that intentionally need these.

Gap identified by PR #1004 (@PeterFile).

* feat(delegate): add observability metadata to subagent results

Enrich delegate_task results with metadata from the child AIAgent:

- model: which model the child used
- exit_reason: completed | interrupted | max_iterations
- tokens.input / tokens.output: token counts
- tool_trace: per-tool-call trace with byte sizes and ok/error status

Tool trace uses tool_call_id matching to correctly pair parallel tool
calls with their results, with a fallback for messages without IDs.

Cherry-picked from PR #872 by @omerkaz, with fixes:
- Fixed parallel tool call trace pairing (was always updating last entry)
- Removed redundant 'iterations' field (identical to existing 'api_calls')
- Added test for parallel tool call trace correctness

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

* feat(stt): add free local whisper transcription via faster-whisper

Replace OpenAI-only STT with a dual-provider system mirroring the TTS
architecture (Edge TTS free / ElevenLabs paid):

  STT: faster-whisper local (free, default) / OpenAI Whisper API (paid)

Changes:
- tools/transcription_tools.py: Full rewrite with provider dispatch,
  config loading, local faster-whisper backend, and OpenAI API backend.
  Auto-downloads model (~150MB for 'base') on first voice message.
  Singleton model instance reused across calls.
- pyproject.toml: Add faster-whisper>=1.0.0 as core dependency
- hermes_cli/config.py: Expand stt config to match TTS pattern with
  provider selection and per-provider model settings
- agent/context_compressor.py: Fix .strip() crash when LLM returns
  non-string content (dict from llama.cpp, None). Fixes #1100 partially.
- tests/: 23 new tests for STT providers + 2 for compressor fix
- docs/: Updated Voice & TTS page with STT provider table, model sizes,
  config examples, and fallback behavior

Fallback behavior:
- Local not installed → OpenAI API (if key set)
- OpenAI key not set → local whisper (if installed)
- Neither → graceful error message to user

Co-authored-by: Jah-yee <Jah-yee@users.noreply.github.com>

---------

Co-authored-by: omerkaz <omerkaz@users.noreply.github.com>
Co-authored-by: Jah-yee <Jah-yee@users.noreply.github.com>

tests/agent/test_context_compressor.py

@@ -153,6 +153,47 @@ class TestGenerateSummaryNoneContent:
         assert len(result) < len(msgs)
 
 
+class TestNonStringContent:
+    """Regression: content as dict (e.g., llama.cpp tool calls) must not crash."""
+
+    def test_dict_content_coerced_to_string(self):
+        mock_response = MagicMock()
+        mock_response.choices = [MagicMock()]
+        mock_response.choices[0].message.content = {"text": "some summary"}
+
+        with patch("agent.context_compressor.get_model_context_length", return_value=100000):
+            c = ContextCompressor(model="test", quiet_mode=True)
+
+        messages = [
+            {"role": "user", "content": "do something"},
+            {"role": "assistant", "content": "ok"},
+        ]
+
+        with patch("agent.context_compressor.call_llm", return_value=mock_response):
+            summary = c._generate_summary(messages)
+        assert isinstance(summary, str)
+        assert "CONTEXT SUMMARY" in summary
+
+    def test_none_content_coerced_to_empty(self):
+        mock_response = MagicMock()
+        mock_response.choices = [MagicMock()]
+        mock_response.choices[0].message.content = None
+
+        with patch("agent.context_compressor.get_model_context_length", return_value=100000):
+            c = ContextCompressor(model="test", quiet_mode=True)
+
+        messages = [
+            {"role": "user", "content": "do something"},
+            {"role": "assistant", "content": "ok"},
+        ]
+
+        with patch("agent.context_compressor.call_llm", return_value=mock_response):
+            summary = c._generate_summary(messages)
+        # None content → empty string → "[CONTEXT SUMMARY]: " prefix added
+        assert summary is not None
+        assert "CONTEXT SUMMARY" in summary
+
+
 class TestCompressWithClient:
     def test_summarization_path(self):
         mock_client = MagicMock()