docs: refresh authored content to v0.16 (next; no version cut)

[0xrouss-miden]

Summary

Refreshes the docs-owned content from v0.15 to v0.16 so the authored Rust, TypeScript, React, MASM, and tool examples match the v0.16 API and toolchain line.

This PR prepares the current docs tree for the release. It does not create versioned_docs/version-0.16, update versions.json, or cut the stable snapshot; those remain part of a separate release PR.

static/llms.txt and static/skill.md intentionally carry the post-release 0.16 stable / 0.17 unstable labels. Merge must therefore be coordinated with the v0.16 snapshot cut to avoid publishing those labels early.

Out of scope

• The v0.16 migration guide, owned separately by docs(migration): add the v0.16 migration guide #357.
• Content imported at deploy time from protocol, Miden VM, node, rust-sdk, tutorials, note transport, and bridge portal.
• The final release manifest and generated v0.16 snapshot.

Changes

• Get Started — refresh setup, account, note, storage, and first-contract flows.
• Smart contracts — align account, note, transaction, standards, MASM, and Rust SDK guidance with v0.16; add transaction-fee funding, calculation, inspection, and network-account fee guidance.
• Web and React SDKs — update client setup, lifecycle, hooks, signers, transactions, and local-node testing.
• Tools and tutorial helpers — refresh Midenup, Playground, debugging, pitfalls, and testing guidance.
• Agent entrypoints — update llms.txt and skill.md for the repository split and v0.16 release context.
• Guardian ingestion — pin the released v0.17.0 documentation source.

Verification

Checked on 2026-09-11 against head bf05555daa66eb245376c1a143db9a50ef97187b:

• git diff --cached --check passed before committing the 44 staged files.
• npm run build succeeds locally. No broken anchors originate from /next; broken-link warnings remain, including links into imported Guardian and node pages. This build does not establish that all deploy-time imports at the final release refs are valid.
• node --check scripts/ingest-guardian.mjs passes.
• npm run typecheck fails with diagnostics in files outside the latest commit, including unresolved @theme/* imports.
• All four reported CodeQL checks pass on the current PR head.
• The latest successful full deployment ran on main at 4c9f358, with development refs and Guardian v0.15.0. It does not validate this PR head or Guardian v0.17.0.

Release gates

• v0.16.0 tags exist for node, rust-sdk, and web-sdk.
• Migration guide docs(migration): add the v0.16 migration guide #357 is merged by its owners — merged on 2026-09-11 as 4c9f358.
• Final imported-content refs are selected and ready for the snapshot manifest. Both this branch and main still have the v0.15 manifest. Select the v0.16-compatible refs for every imported source, explicitly include bridge-portal (currently absent), and pin the tutorials source to the intended revision. Guardian v0.17.0 exists and is selected by this PR's deploy workflow, but the snapshot manifest still pins v0.15.0.
• Merge is coordinated with the v0.16 snapshot cut. Prepare the release branch with this PR and the merged migration guide before generating versioned_docs/version-0.16, updating versions.json, and setting manifest version: "0.16" / next_version: "0.17". Keep the agent-entrypoint labels synchronized with the published snapshot.

Snapshot workflow note: cut-versions.yml reads ten INPUT_* variables, but only maps INPUT_BRIDGE_PORTAL_REF into the parsing step. Wire the remaining nine manual inputs, including version_label, before relying on workflow-dispatch overrides; otherwise define every version/ref directly in the release manifest. The current PR branch is one commit behind main (the merged migration guide), so a snapshot cut from this head alone would omit that merge.

Test plan

• Build the release candidate with all imports at the selected refs, including Guardian v0.17.0, then verify the release deployment. PR checks currently cover CodeQL; deploy-docs.yml runs on main pushes or dispatch and publishes to GitHub Pages.
• Verify that the candidate /next/ renders this PR's v0.16 docs before the cut; the current live deployment is from main, not this PR head.
• After the separate snapshot PR, / serves v0.16 and /next/ advances to v0.17 unstable, consistent with llms.txt and skill.md.

[BrianSeong99]

Reviewed the v0.16 content refresh and pushed the remaining onboarding fixes: non-destructive configuration guidance, existing-account imports for external signers, and confirmed native-fee funding before example transactions.

Validation passed: full docs build, strict checks for all 15 extracted TS/TSX blocks, five Rust binaries plus the funding helper, and all five funding regression tests. No broken links or anchors originate from /next.

Approving the content changes. The documented coherent v0.16 testnet toolchain prerequisite still needs release coordination; this is not live-network validation. Repository-wide typecheck failures outside this patch and stable/historical link warnings remain. Snapshot work is separate.