chore: cut 0.2.0 — README, LICENSE, publish metadata, runtime tune, USB identity, F13

Release-prep work for a publish-worthy 0.2.0:

- LICENSE: MIT, © 2026 Stephen Waits.
- README.md: tagline, what-it-does, hardware, build/flash recipes,
  ASCII statechart overview, "Why four hours…" runtime-tuning rationale,
  USB identity section.
- Cargo.toml: 0.1.0 → 0.2.0; description, license, repository, readme,
  keywords, categories; publish = false (firmware, not a library);
  release profile tightened (lto = "fat", opt-level = "z", panic =
  "abort"). Flashed binary stays 47 KB; the size knobs are explicit
  rather than relying on defaults.
- CHANGELOG.md: collapse Unreleased → [0.2.0] - 2026-05-01.
- scripts/tune_runtime.py: 4-D Monte Carlo over (RUN_DURATION, YELLOW_AT,
  RED_AT, FAST_RED_AT). PEP 723 inline deps so `uv run` just works.

Runtime + LED thresholds re-derived from a typical office workday
distribution with a per-minute press-on-warning user model. Joint
optimum:

  RUN_DURATION:                                          4h00m
  YELLOW_AT  / RED_AT  / FAST_RED_AT  (min remaining):   30 / 25 / 20

USB identity:

  VID/PID:      046d:c07d (G502)  →  1209:b0b0 (pid.codes)
  manufacturer: "Logitech"        →  "swaits.com"
  product:      "G502 Mouse"      →  "jiggly"
  bcdDevice:    default 0x0010    →  0x0200 (matches firmware version)
  serial:       (none)            →  RP2040 chip ID as 16 hex chars

Bug fix in the descriptor change: an interim version spoofed the
Logitech Unifying Receiver (046d:c52b). On Linux, `hid-logitech-dj`
matches that exact PID and tries to talk Logitech's HID++ protocol to
enumerate paired wireless devices. The firmware doesn't speak HID++,
so the driver waits through ~10–20 s of control-transfer timeouts on
every plug before unbinding and letting `hid-generic` actually start
polling. macOS has no such driver and was always fast. Moving to a
pid.codes VID routes the device straight to `hid-generic`.

Wake key: tapped Left Shift in early versions to wake the host. In
practice that turned out to be exactly the nightmare scenario it
sounds like — if the deadline preempted the loop between a Shift-down
report and its Shift-up, the host would silently capitalise every
keystroke from the user's real keyboard until the device was unplugged.
Switched to F13: still wakes any modern OS, but no mainstream OS maps
F13 by default, so a stuck F13 has zero visible effect. Also added an
unconditional all-keys-released cleanup report at the end of the wake
action, bounded by KBD_RELEASE_DEADLINE = 100 ms, so even a deadline
that fires mid-press can't leave anything held.

Wake refactor: WakingWithKeyboard and WakingWithMouse use oneshot
`entry:` actions that race their work against an internal deadline via
`embassy_futures::select`; the chart timer (`on(after KBD_PHASE_DURATION)`
/ `on(after MOUSE_PHASE_DURATION)`) advances. Removes a class of "slow
USB ⇒ chart stalls" failure modes from the wake path.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Stephen Waits <steve@waits.net>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.