refactor(rename): branding strings + active-use docs → bitSpire

Final rename commit covering user-facing copy and the docs that
describe current state. The mechanics of the rename are done after
this; the LNbits backend swap (phase 3) is the next concern.

Code branding strings (Lightning invoice descriptions):
  apps/machine/src/services/lightning.ts
  apps/machine/src/stores/atm.ts
  docs/clink-protocol.md  (example code blocks)
    "Lamassu ATM Payment"        → "bitSpire Payment"
    "Lamassu ATM - Cash Out"     → "bitSpire - Cash Out"
    `Lamassu ATM - Buy ${n} sats`→ `bitSpire - Buy ${n} sats`

Top-level docs:
  README.md, CLAUDE.md — title + intro + dir-tree references.
  deploy/nixos/README.md — title + worktree-path commands.
  docs/machine-installation.md — opening line carries the historical
    note ("Lamassu Next" → "bitSpire"). The body still uses
    `/opt/lamassu/` paths and the `lamassu-kiosk` systemd unit
    because the dev branch is moving to NixOS disk-image flash
    (phase 4) — this AppImage-sideload doc represents the legacy
    deploy path. Leaving the LP/lamassu refs in there as part of
    its historical context; a separate doc will describe the
    NixOS path.
  .claude/skills/nostr-check.md — header only.

DELIBERATELY left as "Lamassu Next" (pedagogical / historical):
  - docs/adr/001-hal-architecture.md — frozen ADR; renaming
    distorts the historical decision context.
  - docs/architecture-comparison.md — deliberately contrasts
    "lamassu-server" (prior) with "lamassu-next" (us at the time
    of writing).

NOT done in this commit (deferred to LNbits/clean-up phase):
  - docker/docker-compose.dev.yml container names
    (lamassu-relay, lamassu-bitcoind, etc.) — these belong to the
    LP-bearing dev stack that 3c/3d will significantly reshape.

Verified: pnpm typecheck clean (12/12 cached).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.claude/skills/nostr-check.md

@@ -14,7 +14,7 @@ Where `target` can be:
 - `--events` to validate event structures
 - `--relay` to check relay configuration
 
-## Relevant NIPs for Lamassu ATM
+## Relevant NIPs for bitSpire
 
 ### Core NIPs (Must Implement)
 | NIP | Description | Usage in Lamassu |