Feature: DB/build change tracking, configurable palette overrides, and README overhaul

[chrismac39]

Feature: DB/build change tracking, configurable palette overrides, and README overhaul

Summary

This PR expands gdse in three major areas:

1. Version/freshness tracking

• Adds DB hash tracking across runs.
• Writes run history entries to gdse-db-hash.txt.
• Includes Steam buildid (from appmanifest_219990.acf) and detected patch markers where available.
• Surfaces last/current change summary before running recolor.

2. Palette customization and UX flow

• Adds configurable palette overrides via gdse-palette.txt.
• Adds optional --palette-file <path> support.
• Supports partial overrides with fallback to defaults for unspecified keys.
• Adds interactive prompts:
  • choose default palette vs custom file
  • confirm run with [Y/N] after change summary
• Incorporates non-damage/class-related color behavior updates and tuned defaults for readability on dark tooltips.

3. Documentation overhaul

• Reworks README with clearer setup and usage guidance.
• Adds clickable section index and visual section separators.
• Clarifies Windows/Linux testing context.
• Documents hash/build/patch tracking behavior.
• Documents palette keys, defaults, and one-line override usage examples.
• Cleans up inconsistent wording/typos and outdated flag references.

Why

• Reduce manual update pain after game patches.
• Make color tuning user-configurable without code changes.
• Improve first-run experience and confidence with explicit prompts/summaries.
• Make setup and customization significantly easier for less technical users.

Key implementation notes

• New module: src/user_palette.rs for palette parsing/validation/loading.
• Hash/build plumbing in src/db.rs and src/main.rs.
• Recolor/property logic updates in src/colorize.rs, src/property.rs, src/color.rs, and src/palette.rs.
• Dependency updates in Cargo.toml / Cargo.lock (including hashing/time support).

Files changed

• Cargo.toml
• Cargo.lock
• README.md
• src/color.rs
• src/colorize.rs
• src/db.rs
• src/main.rs
• src/palette.rs
• src/property.rs
• src/user_palette.rs (new)

Validation

• Verified build/check flow during development (cargo check).
• Verified runtime behavior with interactive prompts and generated outputs.
• In-game visual checks performed for palette readability and non-damage defaults.