docs: rename bot from claude-bot to claude in CI and docs

Update all runtime-relevant references to the Forgejo bot username
from 'claude-bot' to 'claude' following the bot account rename.

- .forgejo/workflows/claude.yml: bot_name input
- docs/forgejo.md: setup guide, examples, and inline references
- CLAUDE.md: bot identity description

Test fixtures and historical PRD files are left unchanged as they
use 'claude-bot' as arbitrary mock data or historical record.

Co-authored-by: vtmocanu <vtmocanu@users.noreply.github.com>

.forgejo/workflows/claude.yml

@@ -39,7 +39,7 @@ jobs:
           claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}
           github_token: ${{ secrets.CLAUDE_BOT_TOKEN }}
           bot_id: "48"
-          bot_name: "claude-bot"
+          bot_name: "claude"
           bot_email: "claude@wxs.ro"
           platform: "forgejo"
         env: