Fix first-draft reminders and make the shared Group unlimited

New characters stopped receiving the first skill-draft lightbulb when Group reached its inherited ten-member capacity. Enrollment persisted a guild ID before admission, then login dereferenced a missing cached member and stopped before publishing the saved draft reminder.

The shared Group now admits every character without a member cap. Login repairs partial enrollment and continues safely when a roster entry is missing. Saved offers, skills, SP, currency, consumption and shared/offline EXP are preserved. Ordinary guild capacity remains enforced.

Large rosters use a signed-byte-safe initial snapshot plus existing member packets, compatible with v1.0.7. CI now rolls out the game server only after publishing the current commit's image; a mutable latest tag previously left production running the old image.

Validation:

• Unchanged default source reproduces the exact line-298 login exception and missing lightbulb.
• Full disposable SQL/classless/draft suite passes: 1,202 offline, 353 pool, 27 migration, 22 dialogue and 949 running-server assertions. Real login-handler fixtures cover the eleventh member and partial-enrollment recovery; 300-member fixtures cover packets, reload and shared EXP for one online plus 299 offline members.
• Eight selective rollout/readiness tests and GitLab CI lint pass.
• Offline X11 renders using unchanged production client source matching v1.0.7 consume the actual 300-member server packet stream and pass the original lightbulb interaction checks.

Review evidence archive. Implementation, provenance and validation notes include the existing large-roster presentation limits.

Related to #10 (closed)'s draft flow. Owner review and merge are required. The game server restarts through CI after merge; players reconnect to receive their saved pending reminders. No database reset, migration or new client release is required. This has not been deployed.