feat: add autobahn integration tests - initial batch (CON-249)

[wen-coding]

Summary

Initial batch of autobahn integration tests. Adds make autobahn-integration-test target with 5 tests:

1. Block production — verify height is advancing (via abci_info)
2. Bank transfer — send usei via -b sync, poll for balance
3. Fault tolerance (3/4) — kill one node, chain continues
4. No quorum (2/4) — kill second node, chain halts
5. Recovery — SKIPPED: autobahn node restart not yet supported (CometBFT handshaker can't reconcile app height vs empty block store)

Every test is guarded by assert_autobahn_enabled which checks GigaRouter initialized in all running nodes' logs.

Known workarounds (with TODOs)

• Uses abci_info instead of /status for height because autobahn doesn't update CometBFT block store
• Uses -b sync instead of -b block because CometBFT consensus is disabled in autobahn mode
• 30s stabilization wait for autobahn giga connections to establish

Depends on #3220 (merged), #3224 (merged), and #3243 (pending — height fix required for blocks to produce).

Usage

make autobahn-integration-test

Test plan

• make autobahn-integration-test passes tests 1-4 with fix: autobahn InitChain height mismatch and testApp height tracking (CON-249) #3243 cherry-picked
• make autobahn-integration-test fails test 1 without fix: autobahn InitChain height mismatch and testApp height tracking (CON-249) #3243 (confirms dependency)
• Cluster starts, tests run, cluster stops cleanly

🤖 Generated with Claude Code

[github-actions]

The latest Buf updates on your PR. Results from workflow Buf / buf (pull_request).

Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Apr 14, 2026, 5:23 PM

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 59.20%. Comparing base (9795d18) to head (b363066).

Files with missing lines	Patch %	Lines
...int/cmd/tendermint/commands/gen_autobahn_config.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3234   +/-   ##
=======================================
  Coverage   59.20%   59.20%           
=======================================
  Files        2069     2069           
  Lines      169537   169537           
=======================================
  Hits       100381   100381           
  Misses      60368    60368           
  Partials     8788     8788           

Flag	Coverage Δ
sei-chain-pr	31.31% <0.00%> (?)
sei-db	70.41% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...int/cmd/tendermint/commands/gen_autobahn_config.go	18.18% <0.00%> (ø)

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