docs: fix skill counts, crate list, memory status and telemetry wording

[Zfinix]

TL;DR

The README, MEMORY.md and the example config now match what v0.7.0 actually ships.

Changes

• README: six core skills (adds artifact design) and twelve internal ones, matching aster-skills/src/lib.rs.
• README: the crate list includes aster-voice and aster-jev.
• README: "no telemetry" now says it is off unless you point it at your own OpenTelemetry endpoint, since aster-telemetry exists.
• MEMORY.md: session consolidation is shipped (aster-memory, run after sessions of six or more turns), so it moves out of "deferred" and Stage 2 drops "(next)".
• aster.yaml.example: the theme is default, matching CONFIG.md and the 0.7.0 rename.

Try it

Read the changed sections; no code changed.

Tested

• make check passes: not run, docs-only change. The pre-commit fmt and clippy checks passed on each commit.
• Tried it for real: checked each claim against the code on main (skill lists, crate folders, consolidate.rs, CONFIG.md theme table).