autobahn: feed persistent_state_dir into data WAL (CON-256)

[wen-coding]

Summary

The data layer's block and commitqc WALs were constructed with utils.None[string](), making them no-ops: writes returned success but nothing landed on disk, and NewState loaded an empty WAL on every restart.

The autobahn config file already has persistent_state_dir and it was already wired into the consensus layer. Reuse the same value for the data layer's WAL (via cfg.Consensus.PersistentStateDir) — the two layers write to distinct subdirs under the same root. No new struct field; once BlockDB has a writer the data WAL will go away entirely (TODO in code).

This will enable Upgrade (Major) test for Autobahn. Right now it's stuck because the previous states are lost upon restart.

Visible changes

• gen-autobahn-config --persistent-state-dir flag now defaults to data/autobahn (was: field absent, persistence off). Pass --persistent-state-dir= to disable.
• A relative persistent_state_dir in autobahn.json is now rootified against --home at load time, matching other tendermint config paths.

Test plan

• Autobahn Upgrade Module (Major) passes (was deadlocking before)
• Autobahn Upgrade Module (Minor) passes
• CometBFT Upgrade Module Major/Minor still pass

[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	May 21, 2026, 3:16 PM

[codecov]

Codecov Report

❌ Patch coverage is 14.28571% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.08%. Comparing base (b5fdb12) to head (336de10).

Files with missing lines	Patch %	Lines
...int/cmd/tendermint/commands/gen_autobahn_config.go	0.00%	4 Missing ⚠️
sei-tendermint/node/setup.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3483      +/-   ##
==========================================
+ Coverage   59.06%   59.08%   +0.01%     
==========================================
  Files        2187     2187              
  Lines      182294   182286       -8     
==========================================
+ Hits       107676   107697      +21     
+ Misses      64953    64943      -10     
+ Partials     9665     9646      -19     

Flag	Coverage Δ
sei-chain-pr	63.65% <14.28%> (?)
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
sei-tendermint/internal/p2p/giga_router.go	69.75% <100.00%> (ø)
sei-tendermint/node/setup.go	69.23% <0.00%> (-0.45%)	⬇️
...int/cmd/tendermint/commands/gen_autobahn_config.go	15.38% <0.00%> (-1.01%)	⬇️

... and 46 files with indirect coverage changes

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[cursor]

PR Summary

Medium Risk
Enables on-disk persistence for Autobahn’s data-layer WALs and changes the default behavior of gen-autobahn-config to persist state, which can affect restart/recovery and filesystem paths.

Overview
Autobahn persistence is now enabled end-to-end by default. gen-autobahn-config adds a --persistent-state-dir flag (default data/autobahn) and writes it into the generated config; passing an empty value disables persistence.

The Giga (Autobahn) router now initializes the data-layer WALs using cfg.Consensus.PersistentStateDir instead of None, so global block and commit-QC WALs actually survive restarts. When loading Autobahn config, a relative persistent_state_dir is now resolved against the node --home directory to match other Tendermint path handling.

^{Reviewed by Cursor Bugbot for commit 336de10. Bugbot is set up for automated code reviews on this repo. Configure here.}