feat: TikTok and Snapchat integrations

TikTok: getUserProfile, getUserVideos, createVideo (PULL_FROM_URL),
getVideoStatus via Content Posting API v2. Full multi-tenant credential
isolation and audit logging on write operations.

Snapchat: getMe (Login Kit), getAdAccounts (Marketing API). createSnap
throws with a clear explanation that Creative Kit is mobile-only — no
server-side posting API exists.

Platform type, validPlatforms list, and /api/connections endpoint all
updated to include tiktok and snapchat. Architecture diagram updated.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

product/incubation/architecture-system.puml

@@ -72,6 +72,8 @@ package "hermes-mcp  |  Node.js / TypeScript  |  hermes.squaremcp.com" {
     [discord.ts] as c_dc
     [instagram.ts] as c_ig
     [twitter.ts] as c_tw
+    [tiktok.ts] as c_tt
+    [snapchat.ts] as c_sc
     [obsidian.ts] as c_ob
   }
 
@@ -109,6 +111,8 @@ cloud "External Platform APIs" {
   [Telegram Bot API] as tg_api
   [Discord API v10] as dc_api
   [Twitter API v2] as tw_api
+  [TikTok Content\nPosting API v2] as tt_api
+  [Snapchat\nMarketing API] as sc_api
   [Obsidian Vault\nfilesystem] as ob_vault
 }
 
@@ -134,6 +138,8 @@ dispatch --> c_tg
 dispatch --> c_dc
 dispatch --> c_ig
 dispatch --> c_tw
+dispatch --> c_tt
+dispatch --> c_sc
 dispatch --> c_ob
 
 c_wa --> cred_store : getCredential
@@ -142,6 +148,8 @@ c_tg --> cred_store : getCredential
 c_dc --> cred_store : getCredential
 c_ig --> cred_store : getCredential
 c_tw --> cred_store : getCredential
+c_tt --> cred_store : getCredential
+c_sc --> cred_store : getCredential
 
 cred_store --> redis
 wh_router --> redis
@@ -153,6 +161,8 @@ c_li --> li_api
 c_tg --> tg_api
 c_dc --> dc_api
 c_tw --> tw_api
+c_tt --> tt_api
+c_sc --> sc_api
 c_ob --> ob_vault
 
 oauth --> mysql