multi: update btcd to v0.26.2

[Roasbeef]

In this PR, we update the btcd dependency from v0.26.0 to v0.26.2. The v2 submodule migration landed already in #10913, so this is a patch-level bump on top of that work: btcutil/v2 v2.0.1, wire/v2 v2.0.1, and v2transport v1.1.0 come along with the root module.

No API changes in the release, so the bump is a straight go.mod/go.sum update across the root module and the submodules that pin btcd (kvdb, healthcheck, tor, tlv, tools). The psbt + address strictness fixes on btcd master don't have tagged submodule releases yet, so they aren't part of this bump.

[github-actions]

🟡 PR Severity: MEDIUM

gh pr view | 13 files | 116 lines changed

🟡 Medium (10 files)

• go.mod - root dependency version bumps
• go.sum - root dependency lockfile update
• healthcheck/go.mod - module dependency bump (uncategorized submodule)
• healthcheck/go.sum - module dependency lockfile update
• kvdb/go.mod - kvdb submodule dependency bump
• kvdb/go.sum - kvdb submodule lockfile update
• tlv/go.mod - tlv submodule dependency bump
• tlv/go.sum - tlv submodule lockfile update
• tor/go.mod - tor submodule dependency bump
• tor/go.sum - tor submodule lockfile update

🟢 Low (3 files)

• docs/release-notes/release-notes-0.22.0.md - release notes update
• tools/go.mod - tools submodule dependency bump
• tools/go.sum - tools submodule lockfile update

Analysis

This PR is a routine dependency-bump across the repo's Go submodules (root, healthcheck, kvdb, tlv, tor, tools), plus a release notes entry. No source files in any critical or high-severity package (lnwallet, htlcswitch, contractcourt, sweep, peer, keychain, channeldb, funding, lnwire, routing, invoices, etc.) are touched, and only go.mod/go.sum/go.sum lockfiles plus a docs file changed. File count (13) and line count (116) are both well under the bump thresholds. No distinct critical packages are involved. Severity is set to MEDIUM based on the highest-tier files touched (kvdb, tlv, tor, and uncategorized root/healthcheck go.mod changes). Worth a quick check that the dependency version bumps don't pull in breaking changes, but no expert-level review is required.

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