feat: add short code alias for peer connection

[naremloa]

Fixes #11

Adds a 6-character short code as an alternative to sharing the full peer ID during setup. The code only lives during the setup phase. Once the real connection is established, both sides switch to the primary peer ID and the short-code peer is torn down.

Expected behaviour:

• Host sees their code immediately; it stays visible until a peer connects or
  they leave.
• Joiner enters the code → resolved to real peer ID → reload → normal connection completes.
• After connect: chat runs on the real peer ID; the alias is destroyed and
  effectively single-use.
• Existing <domain>/#<full-peer-id> flow unchanged

[Copilot]

Pull request overview

Adds a temporary 6-character alias “peer” to make initial connection setup easier (especially for manual entry), while preserving the existing /#<full-peer-id> linking flow once the real connection is established.

Changes:

• Added alias generation helper with an unambiguous character set.
• Updated Chat to (a) display a host code during setup and (b) resolve 6-char hashes as aliases before reconnecting via the real peer id.
• Added connection timeout/error handling and alias-peer teardown hooks.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
src/Service/ChatHelper.ts	Adds generateAlias() to produce short, human-friendly setup codes.
src/Chat.tsx	Implements alias registration, alias-based join flow, UI for code display/input, and updated connect timeout/error behavior.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[naremloa]

Addressed the Copilot review feedback in 5760f2f.