tix-tracker 0.3.0

A terminal issue tracker: markdown + YAML frontmatter issues with a kanban TUI and CLI
Documentation
# Proposal

## Why

tix already adapts its generated AI-usage guidance to repositories that run Spec Kitty
(detected via a `.kittify/` directory): `tix init-agents` splices in a "Tracking Spec Kitty
tasks with tix" section telling agents to file spec-kitty tasks as `spec-kitty`-labeled tix
issues. OpenSpec (openspec.dev) is a second, increasingly common spec-driven workflow with
the same need — projects keep proposal/spec/task artifacts under `openspec/` and benefit
from the same one-line board tracking for their changes and tasks. tix should treat
OpenSpec the way it treats Spec Kitty.

## What Changes

- `tix init-agents` additionally detects an OpenSpec project (an `openspec/` directory at
  the resolved project root) via a single, deterministic filesystem existence check —
  mirroring the existing `.kittify/` check.
- When OpenSpec is detected, the generated AGENTS.md block also includes a
  "Tracking OpenSpec work with tix" section (parallel to the Spec Kitty one) instructing
  agents to file `openspec`-labeled tix issues for OpenSpec changes/tasks, add the
  proposal/spec/plan to the issue body, list, mark done with `--commit <hash>`, and comment.
- The two framework detections compose independently: neither, spec-kitty only, openspec
  only, or both each produce the correct AGENTS.md block with no duplication and
  deterministic output; flipping a detection on/off adds/removes only its own section.
- The baseline state (no framework detected) remains byte-identical to today's frozen
  golden block. No existing spec-kitty behavior changes.
- Unit and integration tests cover the new 4-state detection matrix; documentation records
  the new integration.

## Capabilities

### New Capabilities
- `init-agents`: generation of the `<!-- tix:start -->` AGENTS.md section — governance and
  spec-framework detection (Spec Kitty via `.kittify/`, OpenSpec via `openspec/`) and the
  per-framework task-tracking dogfooding sections spliced into the block.

### Modified Capabilities
- None — `openspec/specs/` is a fresh project with no established capabilities yet; this
  change introduces the first one.

## Impact

- `src/commands/agents.rs` — detection logic, `build_section` signature (framework matrix),
  new OpenSpec section constant, plus unit tests.
- `tests/agents.rs` — integration tests for the openspec detection states (present, absent,
  flip, both).
- `docs/` — new `docs/openspec-integration.md` documenting the OpenSpec integration,
  cross-linked from `docs/spec-kitty-integration.md`.
- `AGENTS.md` (self-hosted follow-up) — regenerate the block and extend the repo-local
  tracking guidance with the OpenSpec workflow.
- No new dependencies; detection stays filesystem-only (no config reads, no network),
  preserving the existing determinism/non-functional constraints.