pakka v0.6.0

Correctness and performance hardening release.

13 fixes across compression, validator, recall, statusline, and commitgate:

• recall: non-EOF read errors no longer advance last_offset (silent index data loss fixed)
• compress: language tags preserved on code fences in non-strict modes
• compress: consecutive-only heading dedup (non-consecutive headings preserved)
• compress: inflations now metered (honest savings accounting)
• linguistic: maybe/perhaps removed from drop list (no more epistemic inversion)
• linguistic: article-a rule case-sensitive (Plan A, vitamin A preserved)
• validator: reInteger (ports/timeouts/counts), extended rePathAbs delimiters
• commitgate: session nonce in Reviewed-by-pakka trailer (forgery prevention)
• audit/meter/commitgate: shortSID sanitized to [A-Za-z0-9_-] (path traversal fixed)
• statusline: transcript cache with mtime/size invalidation (O(1) hot render)
• statusline: git rev-parse memoized within render (O(1) subprocess calls)

Identified by 4-agent adversarial review. See adversarial-review-2026-05-08.md.