feat(read): add notes read for convention-aware body reading

[olavostauros]

Summary

Closes #126

Adds notes read <file> — the convention-aware read command that returns the visible Markdown body without YAML frontmatter by default. This builds on the parser foundation from PR #127 (notes parse) and establishes the CLI interface the issue proposed.

Changes

• .mise/tasks/read — New uv-based Python mise task (same pattern as .mise/tasks/parse):

  • Returns visible body by default (frontmatter stripped)
  • --json flag outputs structured components (frontmatter, body, diagnostics)
  • --with-frontmatter flag includes YAML frontmatter in plain text output
  • Leverages existing note_components parser library
  • Error handling for missing notes and non-UTF-8 files

• test/read.bats — 10 tests covering:

  • Plain notes → body returned without frontmatter
  • Frontmatter notes → frontmatter stripped by default
  • --with-frontmatter → frontmatter included
  • --json → structured output with correct components
  • --json for plain notes (no frontmatter present)
  • Malformed frontmatter → treated as visible body
  • Missing notes → error message
  • Slug resolution → notes read slug resolves from notes dir
  • Absolute path resolution → notes read /path/to/file.md
  • --json diagnostics field present

• README.md — Updated quick start, daily workflow, what notes manages, and gotchas sections with notes read documentation

Test plan

• All 10 new tests pass locally
• Pre-existing parse.bats failures are environment-specific (mise/rudi install issue, not caused by this PR)
• notes read uses the same path resolution and parser as notes parse