feat(cli): add timeline command for annotated cook milestones

[jongio]

Adds a timeline command that turns a saved cook into an annotated timeline. It reads an archive, picks a probe channel, and marks the milestones worth knowing about: the start, the low point, the longest stall, the first crossing of a target temperature, the peak, and the end. Each line shows elapsed clock time, the temperature, and a short label, so you can read the shape of a cook at a glance instead of scrubbing through every reading.

What is new

• SDK: buildCookTimeline(readings, options) in packages/sdk/src/timeline.ts. Pure and side-effect free. Stall detection runs in linear time using a sliding window with monotonic min/max deques. Non-anchor milestones that land on the first or last reading fold into the start and end lines, and when two milestones share a reading the more specific one wins (target over stall over peak over low).
• CLI: thermoworks timeline <SERIAL> [--archive ID] [--channel N] [--target F] [--json]. Defaults to the latest archive. Converts Celsius readings to Fahrenheit before analysis.
• Docs: entries in packages/cli/README.md and docs/cli-reference.md.
• Tests: SDK unit tests for the milestone logic and CLI tests for parsing, formatting, and the handler paths.

Example

Timeline for Brisket 2026 - Meat 1 (182 readings)
  0:00   38F  start   Cook started at 38F
  3:12  151F  stall   Stall began near 152F, held 78m
  9:41  203F  target  Hit target 203F
 10:15  204F  peak    Peaked at 204F
 10:32  201F  end     Cook ended at 201F
  Min 38F, max 204F over 632m.

Verification

• pnpm --dir packages/sdk typecheck && test (488 tests)
• pnpm --dir packages/cli typecheck && test (891 tests)
• pnpm lint

Closes #284