release: FixMap v0.8.3

[aryamthecodebreaker]

Why

The independent post-release audit reproduced #398 against the immutable published @aryam/fixmap@0.8.2 package. PR #435 fixes the validator on main; this patch release makes that correction available through npm and the MCP Registry.

Release scope

• bump root, core, CLI, Action, web dependency, lockfile, and MCP manifest metadata to 0.8.3
• update current install/Action examples
• add focused v0.8.3 changelog and README notes
• preserve apps/web at its private 0.0.0 version
• preserve all optional @emnapi lockfile entries

No ranking behavior or evaluation input changed.

Independent verification

• 414 workspace tests passed
• typecheck and lint passed
• production build passed (all 11 static pages)
• production audit: 0 vulnerabilities
• Action metadata and bundle parity passed
• server manifest and package dry-run passed
• CLI/Action/workspace smoke passed
• held-out: 7/12 Top-1, 8/12 Top-3, 9/12 Top-5
• external: 11/16 Top-1, 16/16 Top-3/Top-5
• adversarial: 8/8, zero false-confidence findings
• 1000-file scanner benchmark passed
• production website HTTP/browser checks passed with zero console errors