docs: reduce the transition contract to the current specification

[okhsunrog]

Make docs/notes/app-state-transitions.md read as the current specification instead of a thousand-line mix of the agreed design, ten dated implementation stages and amendments appended at the end, and retire the stale statements that rewrite exposed elsewhere. Several statements in the contract's middle sections were no longer true (the startup intent "consumed" by the first suite, the transition-driven confirmation, cached tiles overlaid with a note), and agents reading the note reproduced them.

• Sections 1–12 keep their numbers, because code comments and the other docs cite §1–§9, and are rewritten to what holds now: the coordinators and the recorded deviation from a single presentation revision (§1); the startup intent as ensure (§2); the operation observer (§3); read reasons, stale marks, the app-VPN observation and routing knowledge (§5); the measurement key and the applicability table as implemented (§6); the run coordinator's states, the three ways a suite starts and the owed confirmation (§7); the presentation, the Situation, the surfaces and the Dashboard projection (§8); what capture implements and what it still only designs (§9); a new invariant I17 for projections; updated T12/T27 and new T31/T32 traces (§11); the validation boundary with the known gaps (§12).
• Sections 13–22 move verbatim into docs/notes/app-state-transitions-history.md, keeping their numbers, with a preface saying what they are. Every reference to a moved section points at its new home: observation-coordinator.md, diagnostics.md, limits.md, the diagnostics analysis, and one KDoc in ConfigCoordinator.kt.
• Stale statements elsewhere: lsposed/AGENTS.md still described DiagnosticsCache as projecting runs onto the NotRun/Running/Blocked/Failed/Ready states retired in refactor(lsposed): retire the transitional diagnostic state facade #338; observation-coordinator.md described ReadReason.Transition as the VPN transport callback that fix(lsposed): track app VPN state directly #344 replaced with the poller; the UI presentation review's header listed two decisions the owed confirmation superseded. All three corrected.
• docs/notes/state-refactor-handoff.md had every item closed and was still listed as "next steps": removed with its README entry. docs/README.md lists the contract and its history.

Rebased on main after #345; describes the design as merged.