Feature/dirty line highlight

[kibi2]

Summary

This PR introduces deferred repair support and restructures the internal buffer/model pipeline.

The main change is replacing the old redraw-based workflow with a repair-based workflow centered around dirty state tracking.

User-facing changes

• Remove :Tir redraw
• Add :Tir repair [enable|disable|toggle]
• Add dirty table line highlights
• Add configurable highlight groups for dirty markers
• Add deprecation warning for :Tir redraw

Internal changes

• Rename reconcile-based APIs to repair
• Introduce dirty range tracking
• Rename INVALID namespace/state to DIRTY
• Rename vim_* modules to buf_* modules
• Rename tir_text.lua to tir_buf.lua
• Move reconcile/update logic into pipeline modules
• Clear dirty ranges after write
• Improve Range utilities and naming consistency

Notes

Deferred repair mode allows users to temporarily keep malformed tables while maintaining internal attrs/model consistency.

Dirty lines are tracked incrementally via on_lines and visualized using extmarks/highlights.

[codecov]

Codecov Report

❌ Patch coverage is 95.09537% with 18 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
lua/tirenvi/app/pipeline.lua	96.36%	4 Missing ⚠️
lua/tirenvi/editor/commands.lua	75.00%	4 Missing ⚠️
lua/tirenvi/io/dirty.lua	72.72%	3 Missing ⚠️
lua/tirenvi/core/dirty_range.lua	97.05%	2 Missing ⚠️
lua/tirenvi/io/buf_state.lua	94.28%	2 Missing ⚠️
lua/tirenvi/util/range.lua	88.88%	2 Missing ⚠️
lua/tirenvi/parser/flat_parser.lua	0.00%	1 Missing ⚠️

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