fix(kona): enforce strict frame ordering in ChannelAssembler

[sebastianst]

Summary

• Add OrderedChannel — a simplified channel type that enforces strict sequential frame ordering (frame.number == inputs.len()), matching op-node's requireInOrder Holocene behavior
• ChannelAssembler (post-Holocene only) now uses OrderedChannel instead of Channel
• Existing Channel (out-of-order tolerant) stays in ChannelBank for pre-Holocene — independent types, no shared code, clean deprecation path
• OrderedChannel is simpler: Vec<Frame> instead of HashMap, no pruning, is_ready() is just self.closed

Fixes ethereum-optimism/optimism-private#482

Test plan

• 10 unit tests for OrderedChannel: ordered acceptance, out-of-order rejection, ID mismatch, double close, attack scenario (cross-tx out-of-order frames), single-frame channel, L1 inclusion tracking
• All 5 existing ChannelAssembler tests pass unchanged
• Clippy clean, formatted with just f

🤖 Generated with Claude Code

🧠 Note that I choose to create a new OrderedChannel type rather than add more logic to the existing channel because we want to deprecate pre-Holocene derivation soon and then we can just throw out the old Channel which allowed unordered frames. The ordered channel add_frame implementation is much simpler.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.8%. Comparing base (53d3861) to head (74e92c3).
⚠️ Report is 7 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #20011      +/-   ##
===========================================
+ Coverage     74.5%    76.8%    +2.2%     
===========================================
  Files          193      506     +313     
  Lines        10734    64204   +53470     
===========================================
+ Hits          8002    49325   +41323     
- Misses        2588    14879   +12291     
+ Partials       144        0     -144     

Flag	Coverage Δ
cannon-go-tests-64	?
contracts-bedrock-tests	?
unit	76.8% <100.0%> (?)

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

Files with missing lines	Coverage Δ
...col/derive/src/stages/channel/channel_assembler.rs	94.5% <ø> (ø)
rust/kona/crates/protocol/protocol/src/channel.rs	94.8% <ø> (ø)
...na/crates/protocol/protocol/src/ordered_channel.rs	100.0% <100.0%> (ø)

... and 696 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.