feat(coding-agent): support line ranges in @file references

[muyiyr]

Summary

• support 1-based inclusive #L<start>-L<end> selectors on CLI @file references
• preserve literal filenames and existing path recovery, reject image ranges, and align EOF handling with the read tool
• include effective line metadata in file prompt tags and cover prompt delivery through the faux-provider harness

Closes #7673

Testing

• node ../../node_modules/vitest/dist/cli.js --run test/suite/regressions/7673-file-line-ranges.test.ts test/block-images.test.ts test/image-resize-callers.test.ts (23 passed)
• npm run check:browser-smoke
• npm run check (local ignored model snapshot lacks GitHub Copilot grok-4.5 and Groq qwen/qwen3.6-27b; GitHub Actions uses hydrated model data)
• ./test.sh (same local model snapshot failures plus missing workspace dist artifacts in the fresh clone)

[petrroll]

I don't think OP is asking to solve it for CLI mode, I'd expect their plugin either communicates with open TUI instance or runs one via RPC / JSON and sends normal prompts where Pi doesn't parse stuff, as someone said in the issue.

In other words this is not fixing their problem.

[badlogic]

aye, @petrroll is right here.

[muyiyr]

@badlogic @petrroll Thanks for the clarification and for taking the time to explain. I understand now!