Docs: public copy, site presentation, release-gate review (D533, D534)

Public-copy language pass, homepage restructure and Documentation rename,
404 page, dead-anchor and permalink fixes, release-gate sign-off, and the
pre-release review fixes of the 2026-10-05 batch (probe-doc drift,
build-path hygiene, verify.sh and capture safety).

Refs: D533 D534

docs/fidelity.md

@@ -0,0 +1,72 @@
+---
+title: Fidelity status
+description: How faithfully the port reproduces the N64 game: unmodified decompiled logic, Makefile-mirrored region macros, one game-logic-adjacent change, and PRNG notes.
+date: '2026-10-05'
+modified_time: '2026-10-05'
+---
+
+## Fidelity status
+
+This page answers one question plainly: *how faithfully does the port
+actually reproduce the original N64 game's logic*?
+The audit was run end-to-end on 2026-09-15 and re-verified for the v0.3.0
+release bundles on 2026-09-18.
+
+**v0.5.0 update pass, 2026-10-05:** two of the checks were re-run
+directly against the current tree — the region build macros were
+compared line-by-line against the original N64 Makefile's macro sets
+(all three regions match exactly), and the library file classification
+(which original files compile versus get PC-shimmed) was re-checked
+against the project's own ground-truth manifest (the CMake build
+compiles the libultra and libultrare audio sets, the gu matrix helpers,
+and `io/vitbl.c` only — no silent gaps, no silent duplicates). The
+full game-logic audit was not re-run in this pass; recent `src/game`
+edits on the release branch are finding-gated (for example the D519
+front-end options work, and a model-c scripted-camera clamp removal
+that returned those files to pure decompilation). The full engineering
+record behind each item is in the project's finding log
+([`docs/dev/findings.md`](https://github.com/jkdansereau/goldeneye-pc-port/blob/main/docs/dev/findings.md)).
+
+## The rule and what was checked
+
+The port's non-negotiable rule is that decompiled game logic is never
+changed — only genuine N64-hardware dependencies get a PC-side
+replacement, in the `port/` layer. This was audited directly:
+
+- **Region build macros** exactly mirror the original N64 Makefile's macro
+  sets for all three regions — verified line-by-line (re-run 2026-10-05).
+- **The audio/library file classification** (which original files compile
+  vs. get PC-shimmed) exactly matches the project's own ground-truth
+  manifest — no silent gaps, no silent duplicates (re-run 2026-10-05).
+- **The one shipped game-logic-adjacent change** (a portal-culling
+  float-precision fix, D271) is `#ifdef PORT`-gated, documented in the
+  finding log, and moves *toward* matching N64 behavior, not away from it.
+  Every other deviation from the decompiled source is one of the documented
+  32→64-bit pointer-width ABI corrections described above.
+
+## One issue, found and fixed before v0.3.0 shipped
+
+The port's random-number generator (`port/src/random.c`) was documented
+as a bit-exact port of the N64's PRNG, but wasn't — a shift-operation
+helper didn't match the real MIPS64 instruction semantics it was meant to
+mirror. This was independently confirmed by hand-tracing the assembly
+against the C port, tracked as finding D284, and fixed before the release
+(verified clean across a full level sweep — all 20 missions plus the
+ending sequence — no crashes). It affected loot placement, AI behavior
+variance, and replay-state determinism from the very first random draw,
+in every release before v0.3.0. Because of the fix, RNG-derived output —
+including the save-file CRC — changed, which meant existing save files
+and any previously recorded replays no longer validate; v0.3.0's release
+notes describe the automatic save migration that handles this. We'd
+rather say this plainly than let a "verified bit-exact" claim stand
+uncorrected, both when it was wrong and now that it's fixed.
+
+Everything else checked (the documented ABI/pointer-width exceptions used
+for the 32-to-64-bit transition, a sample of the finding log's own claimed
+fixes against the actual current code) matched what's documented.
+
+---
+
+*This page is kept current alongside future releases. Its source review is a
+manual, human-reviewed process today — see the project roadmap for plans to
+partially automate the mechanical parts of it.*