fix(channels): strip Share modal — remove redundant URL copy + duplicated key field (#1101) (#1103)

## Summary

Strips the Share Channel modal (shipped in #1090) down to its
essentials. Removes redundant affordances that the QR already provides.

## What changed

**Removed from the Share modal:**
- The URL text printed inside the QR box (the QR encodes the URL)
- The inline Copy Key button inside the QR box (overlapped the image)
- The `meshcore://` URL input field below the QR
- The Copy URL button next to the URL field

**Result — the modal now contains exactly:**
- Title `Share: <Channel Name>`
- QR code (just the QR `<img>`, nothing else in that box)
- Hex Key field with a single Copy button BELOW the QR
- Privacy warning
- ✕ close button (top right)

## Implementation

- `public/channels.js` — drop the `meshcore://` URL field-group from
share modal markup; `openShareModal()` no longer looks up `#chShareUrl`
or builds a URL into a field; pass `{ qrOnly: true }` when calling
`ChannelQR.generate` so the QR box renders ONLY the QR image.
- `public/channel-qr.js` — `generate(name, secret, target, opts)` now
accepts `opts.qrOnly` which short-circuits before appending the inline
URL line + Copy Key button. Default behaviour (no opts) unchanged, so
the Add-Channel "Generate & Show QR" flow is untouched.

## Tests (TDD: red → green)

- New: `test-channel-issue-1101.js` (static grep) — asserts the URL
field is gone from markup, `openShareModal` no longer references it, and
`ChannelQR.generate` honours `qrOnly`.
- Updated: `test-channel-issue-1087.js` and
`test-channel-issue-1087-e2e.js` — those previously asserted the URL
field's presence (which is exactly what #1101 removes); they now assert
ONLY the hex key field exists, AND that `#chShareQr` contains exactly
one `<img>` and no `.channel-qr-url` / `.channel-qr-copy` children.
- Wired into `.github/workflows/deploy.yml` `node-test` job.

Commit history shows red (test commit `c0c254a`) → green (fix commit
`6315a19`) per AGENTS.md TDD requirement.

E2E assertion added: test-channel-issue-1087-e2e.js:184

## Acceptance criteria

- [x] Share modal contains only: QR, "Copy Key" button, privacy warning
- [x] No "Copy URL" affordance anywhere in the modal
- [x] No duplicated hex key field below
- [x] E2E test asserts the absence of the removed elements

Fixes #1101

---------

Co-authored-by: meshcore-bot <bot@meshcore.local>
Co-authored-by: clawbot <clawbot@users.noreply.github.com>

.github/workflows/deploy.yml

@@ -90,6 +90,7 @@ jobs:
           node test-channel-qr-wiring.js
           node test-channel-modal-ux.js
           node test-channel-issue-1087.js
+          node test-channel-issue-1101.js
           node test-pull-to-reconnect-1091.js
           node test-channel-fluid-layout.js