feat: add isolated multi-account profiles

[dapi]

Summary

• add global account selection via --account and TGCLI_ACCOUNT
• isolate config, MTProto session, archive DB, locks, downloads, service state, labels, and logs per account
• bind named profiles to the authenticated phone and immutable Telegram user ID
• fail closed on crossed identities, corrupt metadata, path traversal, symlink/hardlink aliases, stale registry locks, and concurrent registry updates
• preserve the existing default store and session without migration

Verification

• Node 25.9.0 full suite: 17 files, 289 tests
• repeated concurrent account-registration stress test
• launchd exact-label and named-service isolation tests
• independent security/correctness review passed
• live E2E with default and kz accounts authenticated simultaneously
• primary and kz session paths and inodes are distinct
• default phone/session remained authenticated and unchanged by named-account setup

Live result

The second account was registered as profile kz and authenticated successfully. The legacy default account remains authenticated independently. No logout, reset, migration, or session copying was performed.