[Feature]: Refresh README to reflect current addon state

[Xerrion]

Problem

The README is approximately two major versions behind the addon's current state on master:

• Supported Versions table is missing Retail Interface 120005 (currently shipping in DragonLoot.toc) and lists outdated build numbers
• Commands table is missing /dl enable, /dl disable, /dl testroll loop, /dl testroll stop, plus aliases (options, settings, ?); the /dl (no args) description is wrong - it toggles the addon, not ""shows help""
• Features list is missing every major addition since 0.7.0: ElvUI conflict detection (0.13.0), redesigned tabbed Options UI (0.12.0), DragonWidgets shared widget library (0.10.0), expanded appearance options (0.8.0), direct loot history tracking via CHAT_MSG_LOOT (0.7.0), Transmog roll type, item-level overlay, hide-after-voting, LibAnimate animation styles
• The DragonLoot_Options LoadOnDemand companion sub-addon is not documented anywhere
• 11 shipped locales (enUS, deDE, esES, esMX, frFR, itIT, koKR, ptBR, ruRU, zhCN, zhTW) are not mentioned
• License footer link references the main branch; the actual default branch is master

Proposed Solution

Refresh README.md to reflect current state on master:

• Fix the Supported Versions table to match DragonLoot.toc exactly
• Rebuild the Commands table to include all 13 verbs and aliases, with accurate descriptions
• Rewrite Features to cover the 0.7-0.13 additions
• Add a Sub-addons section documenting DragonLoot_Options
• Add a Localization section listing the 11 shipped locales
• Add an ElvUI Compatibility section
• Update Contributing to mention just, mise, busted, stylua
• Fix the License link to master

No source code changes.

Alternatives

Patch only the most egregious errors. Rejected: the README is far enough behind that targeted patches would still leave most claims wrong.