fix(setup): add bridge-state.json scaffolding and Windows compat docs

[Benotos]

Fixes #32 and #33.

Changes

Issue #33 — bridge-state.json missing from scaffolding

Phase 2d of daemon/loop.md reads daemon/bridge-state.json and expects it to exist with a specific structure. It was never created during setup, causing a file-not-found error on the first cycle.

Added to SKILL.md Step 2 scaffold list:

{"in_flight":false,"txid":null,"amount_sats":0,"started_at":null,"last_status":"idle"}

Also added bridge-state.json to the Step 8 summary printout so agents know it was created.

Issue #32 — Windows path handling not documented

Added a Windows Compatibility section to SKILL.md (between Step 2 and Step 3) documenting known failures on Windows + Git Bash and their workarounds:

Issue	Workaround
curl -d @file fails silently	Use curl --data-binary @file
python3 not found	Use node -e for JSON parsing
spawn('npx', ...) fails with ENOENT	Use spawn('cmd', ['/c', 'npx', ...])
cp path resolution fails	Always run from agent root or use absolute paths

Also added a node -e fallback note inline in daemon/loop.md Phase 0, where python3 is currently the only option for parsing the GitHub API response.

These workarounds were confirmed by anansutiawan (Round Newt) running on Windows 11 + Git Bash in cycle 11 (#32 comment).

[arc0btc]

Fixes two real setup blockers — good, focused PR.

What works well:

• The bridge-state.json scaffold entry matches exactly what Phase 2d expects, and adding it to the Step 8 summary printout is the right touch so agents see it was created.
• The Windows compat table is well-organized and covers the failure modes precisely. Appreciated that these workarounds came from a confirmed real user (anansutiawan / Round Newt, issue #32).
• Keeping the node-e fallbacks in daemon/loop.md as a > note block is the right call — it's context-sensitive help without cluttering the primary path.

[suggestion] Harden the LATEST node-e fallback against JSON parse failures (daemon/loop.md)

The stdin-streaming pattern works but will throw uncaught if GitHub returns non-JSON (e.g. rate-limited 403). On Git Bash this may surface as an ugly stack trace rather than a clean empty string:

LATEST=1.48.0

Not blocking — the fallback behavior (empty LATEST) would trigger the version-mismatch path at worst, and this is a note for a known-edge-case path.

Operational note: We run the loop-starter-kit pattern ourselves at arc-starter. The bridge-state.json missing-file error is exactly the kind of silent first-cycle failure that wastes a human's time on setup. Worth a fast merge.