Release probbit 0.9.0

[BitmapAsset]

Release probbit 0.9.0 from main after #37 and #38: RFC 0001 (senses, action-addressed feedback), #38 (unsupported is not diverges, the host contract) and the never-tagged 0.8.3 items (probbit check, the GitHub Action, the rule-check demo). 0.10.0 (RFC 0002 part 1, #39 and #40) follows after its fix wave.

What's new in 0.9.0 (the README block)

• Senses and action-addressed feedback (RFC 0001, opt-in): each reading is compared with a learned normal per sense that moves only inside declared caps (why names it); an outcome pays the decision it names, and duplicate, cancelled and unknown payments are refused whole. A persona without the new blocks gives the documents 0.8.2 gave, byte for byte.
• probbit check: one CI gate (prove, fuzz, replay) and a GitHub Action. live verify reports a field a newer engine wrote as unsupported (exit 5), never as a divergence; docs/persona.md §7 states the host contract.
• Measured (BENCHMARKS.md §10, §11): 653 outputs recorded with 0.8.2, 0 differ; habituation, the named past, credit (8,393 payments, 100 % equal to an independent learner), replay and habits pass their bars; the twins bars a1 and a2 fail and are reported as findings.

What this PR changes

• Version 0.9.0: Cargo.toml, the internal path dependencies, Cargo.lock (cargo update --workspace --offline), npm/package.json, docs/probbit.1 (regenerated with probbit man).
• v0.9.0 as the example tag: install.sh, install.ps1, action.yml (its version input named v0.8.3, a tag that never existed), .github/workflows/bench.yml, the installer contract tests; docs/CHEATSHEET.md's title; the strand header example in docs/persona.md §5.7. .github/workflows/check.yml keeps its v0.8.2 case on purpose (an old release without check).
• CHANGELOG: ## 0.9.0 - 2026-10-17 with an upgrade note (live verify exits 5 on a newer engine's strand); the 0.8.3 items kept as ### probbit check and fixes (was 0.8.3, never tagged); ## 0.10.0 - unreleased stays on top.
• README: "The current release is v0.9.0", the action example BitmapAsset/probbit@v0.9.0 and its version input, the "What's new in 0.9.0" block.
• RELEASING.md: the release procedure, the landing-page rule at its head.
• probbit-cli/tests/readme_release.rs: fails when the README's current release disagrees with Cargo.toml (equal on a release, lower on a -dev build) or when the README shows a tag newer than it.
• .github/dependabot.yml: ignore dtolnay/rust-toolchain (its ref is the toolchain the msrv job installs; see build(deps): bump dtolnay/rust-toolchain from 1.78.0 to 1.120.0 #35).

Checks run before opening

• Release build cargo build --release --locked -p probbit-cli (rustc 1.98.1): probbit 0.9.0; docs/probbit.1 regenerated from it.
• git grep -n "0\.9\.0-dev\|v0\.8\.3": only the recorded test fixtures (the strand a 0.9.0-dev build wrote, the 0.8.2 binary's output on it, and the tests that name them).
• cargo publish --dry-run --workspace --locked: probbit-core, probbit-ir, probbit-decide, probbit-cli packaged and verified at 0.9.0 (probbit-wasm has publish = false). npm pack --dry-run in npm/: probbit@0.9.0, 5 files.
• readme_release.rs, compiled alone per case: fails on main before Version 0.9.0-dev; verify reports unsupported fields; host contract paragraphs #38 and after it (the README showed v0.8.3, newer than its current release v0.8.2), passes at 0.9.0 and at a later 0.10.0-dev, fails on a forgotten bump (0.9.1) and on a 0.9.0-dev build naming v0.9.0.
• Gate of this PR's base (main after RFC 0002 wave 0: freeze (RFC draft, bench/body fixtures, seeds and bars) #37 and Version 0.9.0-dev; verify reports unsupported fields; host contract paragraphs #38): MSRV 1.78 build; P0 (bench/individuality/p0.py check): 653 outputs, 0 differ; persona prove, fuzz, lint on sensed.yaml, dispatch-policy.yaml, tutor.yaml: exit 0; python/test_mcp.py: OK; bench/individuality/run.py --only a,b,c,d,e: a1 and a2 fail as recorded in BENCHMARKS.md §10, b1-b5, c1-c4, d and e pass with the recorded numbers.
• P0 with the 0.9.0 build: 653 outputs, 0 differ (629 byte-identical, 24 stderr streams with one notice line), 8 of 8 strands verify.
• The never-post and law-word check on every added public line, RELEASING.md and the release notes: 0 hits.