Bound repository context size in load_repo_context

[coderabbitai]

Summary

Add bounded Markdown context loading to repo_router.py so repository context passed to the LLM has predictable size.

Rationale

load_repo_context() currently reads baseline and intent-matched .agent/**/*.md files in full. Categorizing the query reduces the number of selected files, but a single large selected file can still consume the prompt budget, increase latency, and cause the user query or relevant context to be truncated.

Affected area

• repo_router.py
• load_repo_context()

Required changes

• Introduce a shared capped-read helper for Markdown context files.
• Apply a per-file content limit to operational data, architecture, core context, and instruction files.
• Enforce an overall context-size budget while appending sections.
• Preserve the existing intent-based selection and error logging behavior.
• Mark truncated content clearly in the assembled context.

Acceptance criteria

• No individual Markdown context file can exceed the configured per-file cap in the LLM context.
• The assembled repository context cannot exceed a configured total budget.
• Existing README truncation remains consistent with the shared limit strategy.
• The existing routing and intent-selection behavior remains unchanged.

Backlinks

• Reported from PR add skills #21: add skills #21
• Review discussion: add skills #21 (comment)

Requested by @kpj2006.