Wire up the upgrade/renew placeholder CTA on denied-resource states

[Lakes41]

Difficulty: Intermediate
Type: feature

Background
The README lists "upgrade/renew placeholders" among the member-dashboard MVP features, and the mock developer controls include a "Denied Resource" scenario preset (free tier user denied access to Alpha Docs) specifically for testing this state.

Problem
The denied-resource state currently shows an upgrade/renew placeholder with no real interaction — it doesn't link anywhere or explain what upgrading/renewing would involve, leaving a dead-end UX for members who hit a gate.

Expected outcome
When a member is denied access to a gated resource due to tier/expiration, the denied state clearly explains why (using policy/membership data already available from /v1/policies and /v1/members/:address/membership) and the CTA button leads to a dedicated (still-placeholder-content-fine) upgrade/renew info page instead of doing nothing.

Suggested implementation

• Update the components/gated.tsx denied-state rendering to surface the specific reason (expired vs. insufficient tier vs. no roles) using existing membership/policy data.
• Add a simple /upgrade (or similar) route explaining next steps, linked from the CTA.
• Verify the "Denied Resource" and "Expired Member" mock scenario presets both route to sensible denied-state copy.
• Add tests (or Storybook-style manual verification steps in the PR) covering each denial reason.

Acceptance criteria

• Denied state shows the specific reason for denial, not a generic message
• CTA links to a real (even if simple) upgrade/renew page
• Behavior verified against both "Denied Resource" and "Expired Member" mock presets

Likely affected files/directories

• components/gated.tsx
• app/ (new upgrade/renew route)
• lib/api/mock.ts

[NkechiOgbuji]

Please assign to me. Thank you

[grantfox-oss]

🦊 GrantFox — @NkechiOgbuji has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #324)
2. Your PR will be reviewed by the Adamantine-guild maintainers

Good luck! Track your progress on GrantFox.