Add guarded ReShade runtime updates and effects research

[Jumpstile]

Summary

This draft keeps the ReShade scope narrow:

• Fixes the existing-runtime update path so an older installed ReShade DLL can use the already validated automatic download/trust/extraction pipeline after explicit user approval.
• Keeps the prior runtime when the user declines, version metadata is unknown, the latest-version check is unavailable, the trust gate rejects the installer, or any update step fails.
• Removes the misleading implication that TPM currently manages visual-effect packages.
• Adds a research-only visual-effects matrix and real-game evaluation gate for Feature Request: automated ReShade shader/preset browser -- download, menu with descriptions+screenshots, apply #16. No shader downloader, preset generator, effect default, executable add-on, or whole-directory replacement is implemented.

Closes #247
Refs #16

Trust and safety

The update path reuses the official reshade.me URL construction, shared download audit, pinned Authenticode status/thumbprint gate, self-extracting archive validation, and transactional cache promotion. No publisher digest is invented when one is unavailable.

Validation

• Full Pester: 485/485 on Windows PowerShell 5.1 and PowerShell 7.
• Focused ReShade tests: 44/44 on both engines.
• Focused SHA/hash tests: 72/72 on both engines.
• QualitySystem: 16/16 on both engines.
• VirtualBetaTester workflow: 16/16 on both engines.
• Production and changed-test parsing: zero errors on both engines.
• PSScriptAnalyzer Error/Warning with project settings: zero findings.
• ASCII checks for changed PowerShell/TXT/research files: zero non-ASCII bytes.
• InjectionHunter: current scan matches the clean-base finding inventory; no new unresolved finding.
• git diff --check: clean.
• Attribution scan: clean.

No package was rebuilt, no release/tag was changed, and no arcade validation was performed in this branch.

[Jumpstile]

1.0 readiness PR cleanup disposition.

This PR remains potentially relevant to final Version 1.0 because it targets #247, but it must not be merged from its current stale draft state.

Current cleanup classification:

• State: open draft.
• Disposition: candidate Version 1.0 fix, needs rebase/revalidation or replacement PR.
• Base: old pre-RC7 main (639bcbf).
• Current mergeable state: false.
• Validation in the PR body predates the current 656-test baseline and cannot be treated as current release evidence.
• The research-only Feature Request: automated ReShade shader/preset browser -- download, menu with descriptions+screenshots, apply #16 content must remain clearly separated from any runtime ReShade update fix.

Required before merge consideration:

1. Rebase or recreate on current main.
2. Confirm the Existing ReShade runtime updates route to manual instructions #247 fix still applies after RC7 changes.
3. Keep shader/effects research as non-runtime/non-release-authorizing unless separately scoped.
4. Rerun focused ReShade tests.
5. Rerun full Quality suite under Windows PowerShell 5.1 and PowerShell 7 using the current baseline.
6. Run parse, PSScriptAnalyzer, attribution, and stale-release sweeps.
7. Decide whether Existing ReShade runtime updates route to manual instructions #247 is required before final Version 1.0 or can be deferred.

No tag, release, asset, wiki, or final Version 1.0 action is authorized by this comment.