feat: Add configurable MaxChatMessageLength for older protocol versions

[Copilot]

• Analyze codebase: understand GetMaxChatMessageLength() in Protocol16/18 handlers, Settings patterns, ConfigComments patterns
• Add MaxChatMessageLength config option to Settings.cs under AdvancedConfig (default: 0 = auto-detect)
• Add validation in OnSettingUpdate() to clamp the value (0-32767) and warn about potential kicks
• Update Protocol18Handler.GetMaxChatMessageLength() to check the config override
• Update Protocol16Handler.GetMaxChatMessageLength() to check the config override
• Add config comment in ConfigComments.resx and ConfigComments.Designer.cs
• Build and verify the changes compile (0 errors, only pre-existing warnings)
• Run code review (no issues found)
• Run CodeQL security scan (no alerts)
• Decompile MC 1.8 server, modify chat limit from 100 to 256, recompile
• Integration test: MCC with MaxChatMessageLength=256 on modified 1.8 server
  • 101-char message sent and echoed back (exceeds vanilla 100 limit)
  • 200-char message sent and echoed back
  • 256-char message sent and echoed back (at max configured limit)
  • Server logs confirm all messages received at full length
  • Screenshot evidence captured

Integration Test Evidence

Original prompt

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This section details on the original issue you should resolve

<issue_title>[Idea] Add Longer Chat Support for old versions</issue_title>
<issue_description>### Prerequisites

• I have read and understood the user manual
• I made sure I am running the latest development build
• I tried to look for similar feature requests before opening a new one

Console Client Version

Latest

Describe your problem

Currently, In old versions like 1.8.9, the chat message limit is 100 characters. But hypixel supports up to 256 characters.
I suggest adding a configurable option to set the maximum message length to 256.
This would make users can send a long chat in hypixel.

Suggest a possible solution

No response

Attach screenshot here (If applicable)

No response

Minecraft Version

1.8.9

Device

None

Operating System

None</issue_description>

<agent_instructions>Please create a configuration variable that allows for forcing a different maximum chat size on version 1.8 - 1.8.9, but add a warning that this may cause kicking from the server if set incorrectly.

Use the development workflow skill, end-to-end testing skill.
De-compile a 1.8 server, change the max chat size, compile it and then test the change in the mcc. Decompilation instructions are in one of the skills.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes [Idea] Add Longer Chat Support for old versions #2903

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