fix: harden Discord operations and release v0.1.2

[TheStreamCode]

Summary

Prepare discord-management-mcp v0.1.2 with a complete safety hardening pass and a more professional GitHub presentation.

Changes

• omit invite codes/URLs and webhook credentials from tools and snapshots
• recursively sanitize legacy backups and redact secret-bearing errors
• bound and validate backup files, JSON structure, Discord IDs, enum values, arrays, and mutation payloads
• report partial restore progress truthfully after the first failed operation
• advertise valid root-object output schemas for all 47 MCP tools
• update audited transitive dependencies and group Dependabot security updates
• redesign the README around a package-first quick start, safety architecture, capabilities, and support paths
• add optimized README hero and GitHub social-preview assets
• synchronize package, lockfile, changelog, citation, and release metadata for v0.1.2

Impact

Operators receive stricter fail-closed behavior and less sensitive output. discord_backup_read now validates a local snapshot and returns metadata rather than the complete backup payload. Restore failures retain the pre-restore backup ID and report applied, skipped, and failed operations.

Verification

• npm ci
• npm run release:check -- v0.1.2
• npm run preflight
• 11 test files / 38 tests passed
• npm run pack:check (34 consumer files; repository artwork remains excluded)
• npm audit --omit=dev — 0 vulnerabilities
• npm audit — 0 vulnerabilities
• git diff --check

No live Discord mutation was performed.