Point each reader path at the right pages

[SaladDay]

What changed

Lane E of the docs polish (audit-ia F4, F6, F7; audit-user-pages F1, F3, F6, F7, F8, F11, F12, F14, F15). EN and zh together, zh hashes refreshed.

• Overview is the journey page: two ordered lists whose link texts are the target titles.
• Quickstart: one code group per step ([Python]/[curl], [Default model]/[Your own provider]), no if branch, and the expected output of step 3.
• Agents API guide: oac() helper renamed agents(), 11 Python/curl pairs in code groups, Harness restatements replaced by one link to Harness capabilities, new opening, heading pinned as {#core-extensions}. Every inbound link (docs, contracts, zh) points at #core-extensions; no apps/web link targets it.
• API namespaces and credentials: new opening, no hard-coded route count, trailing duplicate section removed, forwarding links to Console server.
• Concepts: rotation sentence replaced by a link to Operations.
• Run self-hosted Sessions (retitled): lifecycle order, Reference section, WARNING alert, size table, <details> for the download-resume text, linux-arm64 removed (not built).
• Web console (retitled), Console server, Console API usage: new openings, defensive negations and the HTTPS row removed, "sandbox slots" replaced by Sandbox capacity.
• Examples: one-sentence lead, contributor section replaced by a CONTRIBUTING link.
• Screenshots from lane S, each used once: getting-started, issue-key, default-model, session-log, request-log in Web console; connect-host in Run self-hosted Sessions (added to BUNDLED_FILES).
• Link texts equal the target titles in all owned files.

Audit claims found wrong

• Console server Verification step 3 said /v1 sent to the console answers 404; services/web/core_routes.go forwards /v1. Removed.
• audit-user-pages F11 keeps the title "Self-hosted executors"; the plan's title table says "Run self-hosted Sessions", which I used.
• audit-user-pages F8 asks for output "captured on mx"; no capture was available, so step 3 shows the first output line with the Items elided.

Checks

Run: make check-docs, node --test website/tests/translations.test.mjs (3 pass), python3 scripts/check-names.py, fence identity EN/zh, compile() of the quickstart snippets.
Skipped: website build and screenshots of the rendered site.

Left for other lanes: "Self-hosted execution" link text in CONTRIBUTING.md and README.zh-CN.md.

---

^{Need help on this PR? Tag @codesmith-bot with what you need.}