refactor: single-user web-based setup — replace env config with Settings UI

Move from multi-user env-var config to single-user web-first architecture:
- Add SetupPage for first-time initialization (replaces /register)
- Add SettingsPage for AI models, exchanges, Telegram, and password management
- Enrich all API route schemas with exact ID usage documentation
- Add PUT /user/password endpoint for in-app password changes
- Remove REGISTRATION_ENABLED, MAX_USERS, TELEGRAM_BOT_TOKEN from env config
- Simplify LoginPage design, remove admin mode and registration links
- Telegram bot now resolves user email for identity display
- start.sh no longer runs interactive Telegram setup

telegram/agent/manager.go

@@ -21,8 +21,9 @@ type Manager struct {
 }
 
 // NewManager creates a Manager. Call api.GetAPIDocs() before this and pass the result as apiDocs.
-// userID is the database user ID the bot authenticates as (used in system prompt context).
-func NewManager(apiPort int, botToken, userID string, getLLM func() mcp.AIClient, apiDocs string) *Manager {
+// userEmail is the registered email shown to the user when they ask "who am I".
+// userID is the internal DB UUID used for API authentication.
+func NewManager(apiPort int, botToken, userEmail, userID string, getLLM func() mcp.AIClient, apiDocs string) *Manager {
 	return &Manager{
 		agents:       make(map[int64]*Agent),
 		lanes:        make(map[int64]chan struct{}),
@@ -30,7 +31,7 @@ func NewManager(apiPort int, botToken, userID string, getLLM func() mcp.AIClient
 		botToken:     botToken,
 		userID:       userID,
 		getLLM:       getLLM,
-		systemPrompt: BuildAgentPrompt(apiDocs, userID),
+		systemPrompt: BuildAgentPrompt(apiDocs, userEmail, userID),
 	}
 }