Release 0.3.0: easy default output with live progress line and chunk map

[Avers]

Summary

Default output (no -v) is now built for general users: a single live [██░░] progress line with an [i/N] step counter (bench-write, bench-read, sparse, retention, boundary, full-verify; quick=3, standard=5, adaptive/full=6 steps) plus a short result — Real size ~= ... and a 64-cell block map (░ untested, █ ok, # fail, ? io-error).

Full 0.2.0-style detail (per-stage headers, rates, summary) lives behind -v/--verbose. Also fixes full-verify progress reporting a real write rate instead of 0.00 B/s.

Bumps VERSION 0.2.0 → 0.3.0 with a CHANGELOG entry.

Verification

• make clean && make clean under -Werror
• make test: 597 checks, 0 failures + CLI smoke passed
• make asan: 597 checks, 0 failures + CLI smoke passed
• make debug builds clean; make lint clean (no clang-tidy, -Werror build)
• Policy × mode matrix: honest→0, alias/stale/unwritten→1, error→4 in both modes; quick/standard→2, adaptive/full→0; bench→0; identify→0
• Default output has zero Stage:/Summary: lines; -v output has zero bar/map lines (byte-checked)

Notes

• Cut from main (single commit); the docs commits on ai/visual-mode are intentionally excluded.
• No changes to safety-critical paths, build system, or dependencies.