docs: comprehensive documentation audit — fix stale info, expand thin pages, add depth (#5393)

Major changes across 20 documentation pages:

Staleness fixes:
- Fix FAQ: wrong import path (hermes.agent → run_agent)
- Fix FAQ: stale Gemini 2.0 model → Gemini 3 Flash
- Fix integrations/index: missing MiniMax TTS provider
- Fix integrations/index: web_crawl is not a registered tool
- Fix sessions: add all 19 session sources (was only 5)
- Fix cron: add all 18 delivery targets (was only telegram/discord)
- Fix webhooks: add all delivery targets
- Fix overview: add missing MCP, memory providers, credential pools
- Fix all line-number references → use function name searches instead
- Update file size estimates (run_agent ~9200, gateway ~7200, cli ~8500)

Expanded thin pages (< 150 lines → substantial depth):
- honcho.md: 43 → 108 lines — added feature comparison, tools, config, CLI
- overview.md: 49 → 55 lines — added MCP, memory providers, credential pools
- toolsets-reference.md: 57 → 175 lines — added explanations, config examples,
  custom toolsets, wildcards, platform differences table
- optional-skills-catalog.md: 74 → 153 lines — added 25+ missing skills across
  communication, devops, mlops (18!), productivity, research categories
- integrations/index.md: 82 → 115 lines — added messaging, HA, plugins sections
- cron-internals.md: 90 → 195 lines — added job JSON example, lifecycle states,
  tick cycle, delivery targets, script-backed jobs, CLI interface
- gateway-internals.md: 111 → 250 lines — added architecture diagram, message
  flow, two-level guard, platform adapters, token locks, process management
- agent-loop.md: 112 → 235 lines — added entry points, API mode resolution,
  turn lifecycle detail, message alternation rules, tool execution flow,
  callback table, budget tracking, compression details
- architecture.md: 152 → 295 lines — added system overview diagram, data flow
  diagrams, design principles table, dependency chain

Other depth additions:
- context-references.md: added platform availability, compression interaction,
  common patterns sections
- slash-commands.md: added quick commands config example, alias resolution
- image-generation.md: added platform delivery table
- tools-reference.md: added tool counts, MCP tools note
- index.md: updated platform count (5 → 14+), tool count (40+ → 47)

website/docs/user-guide/sessions.md

@@ -10,7 +10,7 @@ Hermes Agent automatically saves every conversation as a session. Sessions enabl
 
 ## How Sessions Work
 
-Every conversation — whether from the CLI, Telegram, Discord, WhatsApp, or Slack — is stored as a session with full message history. Sessions are tracked in two complementary systems:
+Every conversation — whether from the CLI, Telegram, Discord, Slack, WhatsApp, Signal, Matrix, or any other messaging platform — is stored as a session with full message history. Sessions are tracked in two complementary systems:
 
 1. **SQLite database** (`~/.hermes/state.db`) — structured session metadata with FTS5 full-text search
 2. **JSONL transcripts** (`~/.hermes/sessions/`) — raw conversation transcripts including tool calls (gateway)
@@ -34,8 +34,22 @@ Each session is tagged with its source platform:
 | `cli` | Interactive CLI (`hermes` or `hermes chat`) |
 | `telegram` | Telegram messenger |
 | `discord` | Discord server/DM |
-| `whatsapp` | WhatsApp messenger |
 | `slack` | Slack workspace |
+| `whatsapp` | WhatsApp messenger |
+| `signal` | Signal messenger |
+| `matrix` | Matrix rooms and DMs |
+| `mattermost` | Mattermost channels |
+| `email` | Email (IMAP/SMTP) |
+| `sms` | SMS via Twilio |
+| `dingtalk` | DingTalk messenger |
+| `feishu` | Feishu/Lark messenger |
+| `wecom` | WeCom (WeChat Work) |
+| `homeassistant` | Home Assistant conversation |
+| `webhook` | Incoming webhooks |
+| `api-server` | API server requests |
+| `acp` | ACP editor integration |
+| `cron` | Scheduled cron jobs |
+| `batch` | Batch processing runs |
 
 ## CLI Session Resume