docs: clarify public development and licensing status

[TechAaroorian]

Summary

• replace ambiguous “open scheduling project” wording
• describe SlotSyncro as a publicly developed portfolio project
• clarify that the repository is source-visible but not open source
• add the All Rights Reserved status to the project-site footer
• surface the licensing distinction near the top of the README
• preserve references to open-source communities as a potential user group

Why

“Built in public” and “open source” have different meanings.

SlotSyncro is developed publicly and its source can be inspected, but the
repository does not grant an open-source license. This update makes that
distinction clear without requiring visitors to find the licensing section at
the bottom of the README.

Verification

• Marketing lint passes
• TypeScript passes
• GitHub Pages static export passes
• /slotsyncro production base path verified
• git diff --check passes

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	99.18%	121 / 122
🔵	Statements	98.38%	122 / 124
🔵	Functions	100%	18 / 18
🔵	Branches	84.28%	59 / 70

File Coverage

No changed files found.

Generated in workflow #32 for commit 4fd79bb by the Vitest Coverage Report Action