PlaceholderAPI Support

• Added built-in PlaceholderAPI integration using the %teams999_*% namespace.
• Added placeholders for team name, colored name, color, level, members, online members, max members, role name, role display name, homes, max homes, warps, alliances, max alliances, MOTD, owner, and trust status.

Command Tab Completion

• Added tab completion coverage for all /team and /ally command paths.
• Added contextual completion suggestions for player names, team names, role names, homes, warps, colors, and role permissions.
• Added full nested completion support for /team role and /team role perm subcommands.

Quality and Stability Fixes

• Fixed alliance listings to show proper team display names instead of lowercase-only names.
• Fixed /team colors list formatting so color entries display cleanly.
• Improved data validation so invalid saved role toggle values are ignored safely during load.
• Improved role loading fallback so invalid saved role colors no longer prevent team data from loading.