refactor(config): migrate remaining 33 cfg_get call sites (#17311)

Completes the cfg_get migration started in PR #17304. Covers the
remaining hermes_cli/ and plugins/ config-access sites that the first
PR intentionally left opportunistic.

Migrated (33 sites across 14 files):

  hermes_cli/setup.py            13 sites  (terminal.*, agent.*, display.*, compression.*, tts.*)
  hermes_cli/tools_config.py      7 sites  (tts.*, browser.*, web.*, platform_toolsets.*)
  hermes_cli/plugins_cmd.py       3 sites  (plugins.*, memory.*, context.*)
  plugins/memory/honcho/cli.py    3 sites  (hosts.*)
  hermes_cli/web_server.py        1 site   (dashboard.*)
  hermes_cli/skills_config.py     1 site   (platform_disabled)
  hermes_cli/plugins.py           1 site   (plugins.disabled)
  hermes_cli/status.py            1 site   (terminal.backend)
  hermes_cli/mcp_config.py        1 site   (mcp_servers.*)
  hermes_cli/webhook.py           1 site   (platforms.webhook)
  plugins/memory/__init__.py      1 site   (memory.provider)
  plugins/memory/hindsight/       1 site   (banks.hermes)
  plugins/memory/holographic/     1 site   (plugins.hermes-memory-store)
  run_agent.py                    1 site   (auxiliary.compression)

The helper supports non-literal keys too, so e.g.
  cfg.get('hosts', {}).get(HOST, {})
becomes
  cfg_get(cfg, 'hosts', HOST, default={})

Migration bugs caught and fixed during this PR:

1. An AST-based batch rewrite naïvely captured the first word token in
   a chain, which corrupted 'self._config.get(...).get(...)' into
   'self.cfg_get(_config, ...)' (dropping 'self.', creating a broken
   method call). Plugins/memory/hindsight caught it via its test suite.
   Fixed manually to 'cfg_get(self._config, ...)'.

2. Import-extension heuristic rewrote multi-line parenthesized imports
   ('from X import (\n  A,\n  B,\n)') as
   'from X import cfg_get, (' — syntactically broken. Fixed by inserting
   cfg_get as the first name inside the parentheses.

Combined with PR #17304, the cfg_get migration now covers:

  PR #17304 (first batch): 20 sites in tools/ + gateway/
  PR #17317 (this one):    33 sites in hermes_cli/ + plugins/ + run_agent.py

Total: 53 sites migrated. Remaining ~8 sites are either:
  - Function-call chains (e.g. '_load_stt_config().get(...).get(...)')
    that would need double-evaluation or a local binding to migrate
    cleanly — intentionally deferred.
  - JSON response-navigation (e.g. 'response_data.get('data',{}).get('web'))
    which is unrelated to config access and shouldn't use cfg_get.

Verified:
- 412/412 tests/plugins/ pass (including the hindsight test that caught
  the self.X regex bug before commit)
- 3181/3189 tests/hermes_cli/ pass (8 pre-existing failures on main,
  verified by git-stash comparison)
- Live 'hermes status' and 'hermes config' render correctly (exercise
  the migrated terminal.backend, tts.provider, browser.cloud_provider,
  compression.threshold, display.tool_progress sites)
- Live 'hermes chat': 1 turn + /quit, zero errors in 11-line log window

No semantic changes — cfg_get was already proven to be a 1:1 match for
the original .get("X",{}).get("Y",default) pattern in PR #17304.

hermes_cli/plugins_cmd.py

@@ -18,6 +18,7 @@ from pathlib import Path
 from typing import Optional
 
 from hermes_constants import get_hermes_home
+from hermes_cli.config import cfg_get
 
 logger = logging.getLogger(__name__)
 
@@ -519,7 +520,7 @@ def _get_disabled_set() -> set:
     try:
         from hermes_cli.config import load_config
         config = load_config()
-        disabled = config.get("plugins", {}).get("disabled", [])
+        disabled = cfg_get(config, "plugins", "disabled", default=[])
         return set(disabled) if isinstance(disabled, list) else set()
     except Exception:
         return set()
@@ -763,7 +764,7 @@ def _get_current_memory_provider() -> str:
     try:
         from hermes_cli.config import load_config
         config = load_config()
-        return config.get("memory", {}).get("provider", "") or ""
+        return cfg_get(config, "memory", "provider", default="") or ""
     except Exception:
         return ""
 
@@ -773,7 +774,7 @@ def _get_current_context_engine() -> str:
     try:
         from hermes_cli.config import load_config
         config = load_config()
-        return config.get("context", {}).get("engine", "compressor") or "compressor"
+        return cfg_get(config, "context", "engine", default="compressor") or "compressor"
     except Exception:
         return "compressor"