Bump MSRV to 1.88, upgrade ratatui 0.30 and crossterm 0.29

[eous]

Resolves two Dependabot security alerts:

• time 0.3.45 → 0.3.47 (stack exhaustion DoS via RFC 2822)
• lru 0.12.5 → 0.16.3 (Stacked Borrows soundness in IterMut)

Collapse 28 nested if/if-let blocks into let-chains, which are stable since Rust 1.87 and now flagged by clippy.

[Copilot]

Pull request overview

Updates the project’s Rust MSRV and dependency set to address security advisories and keep the TUI stack current, while refactoring conditional logic to use stable let-chains.

Changes:

• Bump MSRV to Rust 1.88 across Cargo metadata and documentation/packaging references.
• Upgrade TUI dependencies (ratatui 0.30, crossterm 0.29) and apply security-related dependency updates (notably time and lru) via lockfile refresh.
• Replace nested if / if let blocks with let-chains in multiple sensor/collector paths.

Reviewed changes

Copilot reviewed 24 out of 25 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/sensors/superio/nct67xx.rs	Refactor nested option checks to a let-chain for atomic access logging.
src/sensors/poller.rs	Simplify optional direct-io thread join handling using a let-chain.
src/sensors/i2c/pmbus.rs	Convert page-select and label fix-up conditionals to let-chains.
src/sensors/hwmon.rs	Use let-chain when applying voltage scaling overrides.
src/sensors/gpu_sensors.rs	Use let-chains for optional sysfs reads (AMD busy/VRAM used).
src/sensors/alerts.rs	Collapse cooldown nested checks into a let-chain.
src/sensors/aer.rs	Simplify PCI ID lookup conditional with a let-chain.
src/platform/tegra.rs	Use let-chain for optional GPU load sysfs read.
src/parsers/smbios.rs	Replace nested bounds/value checks with a let-chain in size decoding.
src/output/tui/theme.rs	Refactor COLORTERM detection into a let-chain condition.
src/output/tui/mod.rs	Replace nested cursor/scroll checks with let-chains in key handling.
src/output/tui/dashboard.rs	Use let-chain when conditionally adding the CPU frequency panel.
src/collectors/storage.rs	Replace nested driver/virtio detection with a let-chain.
src/collectors/motherboard.rs	Use let-chain to fill BIOS release only when fields are present.
src/collectors/memory.rs	Use let-chains for optional board config and dmidecode parsing logic.
src/collectors/gpu.rs	Replace nested parsing/normalization checks with let-chains.
src/collectors/cpu.rs	Simplify NUMA meminfo parsing with a let-chain.
README.md	Update documented Rust prerequisite to 1.88+.
packaging/launchpad/README.md	Update Launchpad packaging docs to reference Rust 1.88 toolchain packages.
packaging/launchpad/debian/control	Bump rustc build dependency minimum to 1.88.
PACKAGING.md	Update packaging documentation references from 1.85 to 1.88.
CONTRIBUTING.md	Update contributor Rust prerequisite to 1.88+.
Cargo.toml	Set rust-version = 1.88 and bump ratatui/crossterm versions.
Cargo.lock	Lockfile refresh incorporating dependency upgrades (incl. security updates).
.github/workflows/publish-ppa.yml	Update PPA workflow series/toolchain handling to 1.88 references.

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