chore: prepare the 3.5.0 release (#601)

* chore: prepare the 3.5.0 release

Turns the CHANGELOG's Unreleased section into `## 3.5.0` and bumps
`src.__version__`, the value plugin `ledmatrix_min_version` floors compare
against. No behaviour change; nothing outside the CHANGELOG, `src/__init__.py`
and one docs line is touched.

The staged entries are reshaped into the `### ` subsections every released
section already uses, and the "new modules a plugin may import via `src.*`"
block moves to the top as the plugin-facing summary, the same shape as 3.4.0.
Its floor, written as "the release that ships this" while it was staged, is now
3.5.0, and `docs/SPORTS_UNIFICATION.md` says 3.5.0 for `sports_helpers.py`
instead of "(unreleased)".

Four merged changes had never been written down. They are added under the
subsection each belongs to, from the commits and their measurements:

- the idle back-off clamped to the next kickoff (#599)
- concurrent ESPN date chunks (#596)
- the three web routes that consulted plugin manifests before anything had
  discovered plugins, one of which wrote a plugin API key to config.json in
  plain text (#594)
- the cache permission fix and its systemd unit changes (#593), which get
  their own subsection

No tag and no release: `scripts/check_release_version.py v3.5.0` passes, so
tagging is a separate, deliberate step.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Rqzd6Nz2bQJp5K7DD5dS4X

* ci: let Claude Code Review run on PRs the Claude app opens

The review action refuses a workflow whose actor is a GitHub App unless the
app is named in `allowed_bots`, which this workflow never set:

  Actor is a GitHub App: claude[bot]
  Actor type: Bot
  Action failed with error: Workflow initiated by non-human actor: claude
  (type: Bot). Add bot to allowed_bots list or use '*' to allow all bots.

It aborts about two seconds in, before the diff is read, so the check is red
on every such PR and re-running cannot help: the actor does not change. Until
now no PR here had a bot author, so nothing tripped it.

`'claude'` rather than `'*'`: the action lowercases each entry and strips a
trailing `[bot]` before comparing it to the actor
(`isAllowedBot` in `src/github/validation/actor.ts`), so this admits
`claude[bot]` and no other app. `'*'` would admit any app that can trigger a
workflow here, with a prompt it controls — the action's own docs warn about
that on public repositories, and this one is public.

The write-permission check already allowed the app; `checkHumanActor` was the
only gate.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Rqzd6Nz2bQJp5K7DD5dS4X

---------

Co-authored-by: Claude <noreply@anthropic.com>

src/__init__.py

@@ -4,5 +4,5 @@ LEDMatrix Display System
 Core source package for the LED Matrix Display project.
 """
 
-__version__ = "3.4.0"
+__version__ = "3.5.0"