chore: bump Umbrel Bitcoin UI from 1.1.0 to 1.2.9

[helix-nine]

Summary

Bumps the umbrel-bitcoin submodule from v1.1.0 to v1.2.9 (minor update).

Key upstream changes (v1.1.0 → v1.2.9)

• Unified block architecture — single type, single endpoint, single WebSocket
• ZMQ lifecycle fixes — generation-based start/stop, proper teardown on bitcoind restart/exit
• BIP110 support (v0.4.1) with info popup
• Knots v29.2 (knots20251110) and v29.3 (knots20260210) support
• Sub-1sat/vbyte minrelaytxfee support
• Lightweight getblockstats for bulk cache priming, fixing double-prime on startup

Start9 patches — rebase required

The current submodule (v1.1.0 + 4 patches) has four Start9-specific patches that are NOT incorporated into v1.2.9 upstream. All four need to be rebased onto v1.2.9:

#	Patch	Status	Notes
1	External bitcoind compatibility (2761a34) — removes ConnectionDetails component/route, adds getVersionFromRPC() helper, environment-based bitcoind manager	Not in v1.2.9	v1.2.9 still has ConnectionDetails, Dock connect tab, and original manager.ts. The manager.ts has been refactored upstream (new version helpers, symlink logic), so this patch will need careful conflict resolution.
2	Fetch uptime from RPC + Start9 wording (27395cd) — uses uptime RPC call instead of process-local timer, removes Umbrel-specific wording from UI descriptions	Not in v1.2.9	v1.2.9 still uses Math.floor((Date.now() - startedAt) / 1000). Clean rebase expected.
3	mDNS connection (8792e6e) — ZMQ subscribers connect to bitcoind.embassy instead of 0.0.0.0	Not in v1.2.9	v1.2.9 still uses tcp://0.0.0.0:.... The ZMQ files have been significantly refactored (generation-based lifecycle, proper start/stop/restart handlers), but the connect URL is a single-line change in each file — clean rebase expected.
4	Knots/Core auto-detection (596f765) — header dynamically shows Knots or Core logo/name based on RPC response, generic "Bitcoin" wording in settings	Not in v1.2.9	v1.2.9 header still hardcodes "Bitcoin Knots". Depends on patch 1 (getVersionFromRPC). Clean rebase expected on settings wording.

Proposed new features

The following new upstream capabilities could be exposed to StartOS users:

• BIP110 support — The UI now includes a BIP110 info popup and regex support. Worth verifying this works correctly with the external bitcoind setup.
• Version pinning (v29.2/v29.3) — Upstream now supports multiple Knots versions with a version selector. On StartOS, the Knots version is managed by the bitcoind service, so the version selector UI may need to be hidden or adapted.
• Lightweight getblockstats — Bulk cache priming uses a lighter RPC call, improving dashboard load times.

Action items before merging

1. Rebase all 4 Start9 patches onto v1.2.9 (create a new tag like v1.2.9-start9)
2. Verify the version selector UI doesn't conflict with StartOS's bitcoind service managing versions
3. Test BIP110 popup with external bitcoind setup
4. Build and test on StartOS test server