fix(cosmos): Migrate bundle chunking params on upgrade

[kriskowal]

Description

Chunked artifact bundle uploads fail on chains that upgraded to bundle-chunking
without a migration: the InstallationDeadlineSeconds and
InstallationDeadlineBlocks params were defined in the protobuf but never
registered in ParamSetPairs, so they persisted as 0 (Go zero value). A
deadline of 0 means "expire immediately", causing PruneExpiredBundleInstalls
to remove every pending upload before the first chunk can land.

• Register deadline params in ParamSetPairs so the legacy param store
  round-trips them correctly and they become governable.
• Add Migrate2to3 (consensus version 2 → 3) that calls MigrateParams,
  which treats 0 as "unset" and replaces it with the default (24 h / unlimited
  blocks). This fixes existing chains (e.g. devnet) that already have 0 stored.
• Validate deadline params in ValidateBasic — values below -1 are
  rejected.
• Improve observability in ChunkedArtifactStatus gRPC query — error
  messages now include the artifact ID and distinguish "expired/finalized" from
  "state inconsistency".

Security Considerations

No new authorities or trust boundaries are introduced. The migration only
replaces a zero (immediate-expiry) deadline with the intended default (24 h),
restoring the designed behavior.

Scaling Considerations

No change to resource consumption. The migration touches only the param store
(a single key-value write per param).

Documentation Considerations

Operators upgrading from consensus version 2 to 3 will automatically get the
deadline params populated. No manual steps required. Existing deployments that
already have non-zero values are unaffected.

Testing Considerations

• TestValidateInstallationDeadlineBounds covers boundary validation.
• All 34 pre-existing x/swingset Go tests continue to pass.

Upgrade Considerations

The module's ConsensusVersion is bumped from 2 to 3. The Migrate2to3
migration is registered and will run automatically during the upgrade handler.
To verify on a target chain: query swingset params and confirm
installation_deadline_seconds is 86400 and installation_deadline_blocks is
-1 (unless governance has set different values).

[michaelfig]

LGTM! You and the agents did a good job. :)