Fix some page management and fault handler bugs

[sangho2]

This PR fixes some page management and page fault handling bugs including remap_pages leaks when it fails, incorrect range calculation, page flag misusage, and panics.

[github-actions]

🤖 SemverChecks 🤖 ⚠️ Potential breaking API changes detected ⚠️

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--- failure enum_discriminants_undefined_non_unit_variant: enum's variants no longer have defined discriminants due to non-unit variant ---

Description:
An enum's variants no longer have well-defined discriminant values due to a tuple or struct variant in the enum. This breaks downstream code that accesses discriminants via a numeric cast like `as isize`.
        ref: https://doc.rust-lang.org/reference/items/enumerations.html#assigning-discriminant-values
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.47.0/src/lints/enum_discriminants_undefined_non_unit_variant.ron

Failed in:
  enum DeallocationError in /home/runner/work/litebox/litebox/litebox/src/platform/page_mgmt.rs:233
  enum PermissionUpdateError in /home/runner/work/litebox/litebox/litebox/src/platform/page_mgmt.rs:267
  enum RemapError in /home/runner/work/litebox/litebox/litebox/src/platform/page_mgmt.rs:245

--- failure enum_variant_added: enum variant added on exhaustive enum ---

Description:
A publicly-visible enum without #[non_exhaustive] has a new variant.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#enum-variant-new
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.47.0/src/lints/enum_variant_added.ron

Failed in:
  variant PageFaultError:InvalidFrameAddress in /home/runner/work/litebox/litebox/litebox/src/mm/linux.rs:1059