chore: replace placeholder name for NV28 with FireHorse

[LesnyRumcajs]

Summary of changes

Changes introduced in this pull request:

• replaces the placeholder name with FireHorse to match Lotus logic
• added a generic horse ascii art - feel free to suggest a better one!

Reference issue to close (if applicable)

Closes

Other information and links

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation. All new code adheres to the team's documentation standards,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.

Outside contributions

• I have read and agree to the CONTRIBUTING document.
• I have read and agree to the AI Policy document. I understand that failure to comply with the guidelines will lead to rejection of the pull request.

Summary by CodeRabbit

• Refactor

  • Updated protocol upgrade naming from placeholder to FireHorse across all network configurations (mainnet, testnet, devnet, calibnet).
  • Updated state migration logic to reference FireHorse protocol phase.

• Style

  • Refreshed upgrade notification branding and display.

[coderabbitai]

Walkthrough

The changes replace the placeholder Height::Xxx protocol variant with Height::FireHorse across network configurations, the Height enum definition, state migration, and UI components. This updates height-to-HeightInfo mappings in butterflynet, calibnet, devnet, and mainnet, along with the associated enum variant, version mapping, and display logic.

Changes

Cohort / File(s)	Summary
Network Height Mappings src/networks/butterflynet/mod.rs, src/networks/calibnet/mod.rs, src/networks/devnet/mod.rs, src/networks/mainnet/mod.rs	Updated HEIGHT_INFOS mappings across all network configurations to associate Height::FireHorse instead of Height::Xxx with epoch boundaries (particularly at i64::MAX or FOREST_FIREHORSE_HEIGHT).
Height Enum Definition src/networks/mod.rs	Replaced Height::Xxx variant with Height::FireHorse in the enum definition, updated impl From<Height> for NetworkVersion to map FireHorse to NetworkVersion::V28, and adjusted REQUIRED_HEIGHTS test constant.
State Migration src/state_migration/nv28/migration.rs	Updated manifest lookup to retrieve bundle using Height::FireHorse key instead of Height::Xxx when accessing chain_config.height_infos.
Comments and Display src/rpc/methods/state.rs, src/utils/misc/logo.rs	Updated placeholder comment referencing Xxx to FireHorse in RPC state conversion; replaced reveal_xxx_upgrade() function call and implementation with reveal_fire_horse_upgrade() for V28 logo display.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• chore: nv28 skeleton #6706: Introduced the original Height::Xxx skeleton placeholder that this PR now renames to Height::FireHorse across all height mappings and definitions.
• feat: NV27 butterflynet #6047: Also modifies butterflynet HEIGHT_INFOS entries for network upgrade height schedules.

Suggested labels

RPC

Suggested reviewers

• akaladarshi
• hanabi1224
• elmattic

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 28.57% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: replacing the placeholder name 'Xxx' with 'FireHorse' for NV28 across the codebase.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch replace-placeholder-firehorse

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch replace-placeholder-firehorse

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[codecov]

Codecov Report

❌ Patch coverage is 55.55556% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.91%. Comparing base (919b53e) to head (7936aaf).
⚠️ Report is 3 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/utils/misc/logo.rs	0.00%	2 Missing ⚠️
src/networks/mod.rs	0.00%	1 Missing ⚠️
src/state_migration/nv28/migration.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
src/networks/butterflynet/mod.rs	70.93% <100.00%> (ø)
src/networks/calibnet/mod.rs	100.00% <100.00%> (ø)
src/networks/devnet/mod.rs	93.03% <100.00%> (ø)
src/networks/mainnet/mod.rs	100.00% <100.00%> (ø)
src/rpc/methods/state.rs	44.74% <ø> (ø)
src/networks/mod.rs	88.81% <0.00%> (ø)
src/state_migration/nv28/migration.rs	0.00% <0.00%> (ø)
src/utils/misc/logo.rs	17.77% <0.00%> (ø)

... and 15 files with indirect coverage changes

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