docs: refresh documentation — rename files, fix API responses, add missing content

[allankoechke]

Summary

Comprehensive documentation refresh addressing all issues tracked in idea_board#25.

• Rename all doc files: drop numbered prefixes and update all 53 cross-references across README, QuickStart, doc files, and docker-compose
• Fix 7 confirmed API response mismatches found by comparing docs against source code
• Add missing documentation: WebSocket realtime endpoint, entity list query params, application settings schema, complete MB_* environment variable list, file handling details
• Trim QuickStart.md: cut from 400 lines to ~170 by removing sections already covered in README
• Fix typos and naming errors in scripting.md and installation.md
• Standardize style: remove emoji from headers (consistent with README), drop redundant H1 titles

Changes

Renames (10 files)

• 00.installation.md → installation.md
• 01.cmd.md → cmd.md
• 02.api.md → api.md
• 02.auth.md → auth.md
• 03.rules.md → rules.md
• 05.embedding.md → embedding.md
• 06.docker.md → docker.md
• 11.files.md → files.md
• 12.healthcheck.md → healthcheck.md
• 13.scripting.md → scripting.md

API Response Fixes

Endpoint	Was (wrong)	Now (correct)
GET /api/v1/health	{"status":"ok","uptime":12345}	{"status":"OK"}
POST /auth//refresh	flat {token, user}	{status, data:{token,user}, error}
POST /auth//logout	{message:"Logged out"}	{status, data:{logged_out:true}, error}
GET /sys/logs pagination	page/page_size/total_pages	limit/after/cursor
GET /sys/logs response	{logs:[...], pagination:{...}}	{data:{items, items_count, limit, cursor}}

New Documentation

• WebSocket realtime endpoint (WS /api/v1/realtime/ws) with subscribe/unsubscribe
• Entity list query params (limit, after, sort) — were marked [PENDING], actually implemented
• Application settings schema (appName, baseUrl, maxFileSize, sessionTimeout, etc.)
• Complete MB_* env var table in docker.md (MB_OAUTH_ENCRYPTION_KEY, MB_REALTIME_SSE, MB_REALTIME_WS, MB_LOG_LEVEL, etc.)
• File storage path correction (/files// not //)
• Filename sanitization algorithm and path traversal protection notes

Test Plan

• Verify all doc cross-links resolve to existing files
• Verify Doxygen docs build: cmake -DMB_BUILD_DOCS=ON + --target mantisbase-docs
• Spot-check a few API responses against the documented formats