Refactor: decompose CodebaseAnalytics.vue script section (3200+ lines, 503 functions)

[mrveiss]

Problem

After the initial decomposition in PR #2225 (#1469), CodebaseAnalytics.vue was reduced from 5500 to 4519 lines. However, the script section remains at 3200+ lines with 503 functions/consts — the template extractions were effective but the orchestration logic was left untouched.

The parent component still owns:

• All reactive state declarations (~200 refs/reactives)
• All data-loading/fetching functions (~40 async functions)
• All event handlers for child components
• All WebSocket/polling setup
• Type interfaces used only by specific sub-components

Discovered During

Implementation of #1469 (PR #2225)

Suggested Approach

Extract into focused composables under composables/analytics/:

• useCodebaseState.ts — shared reactive state (rootPath, analyzing, sources, selectedSource, etc.)
• useCodebaseIndexing.ts — indexing job management, progress polling, phase/batch tracking
• useCodebaseSourceRegistry.ts — source CRUD, selection, sharing
• Wire the already-created useCodebaseDataLoaders.ts (see related issue)

Target: reduce parent script to <500 lines of pure orchestration (composable wiring + child event routing).

Impact

Medium — the file is still a maintenance burden. Changes to one data-loading function risk side effects across 500 other declarations.

[mrveiss]

Update from PR #2236 (#1579):

Two composables were extracted, partially addressing this issue:

• useIndexingJob.ts (442 lines) — indexing state, job polling, progress, cancel
• useDashboardLoaders.ts (263 lines) — system overview, communication patterns, code quality, performance metrics + real-time toggle

The script section was reduced from ~3,200 to ~2,734 lines with 192 declarations (down from ~503). Still ~46 async functions remain inline. The next highest-impact extractions would be:

• useCodebaseSourceRegistry.ts — source CRUD, selection, sharing (~100 lines)
• useAnalyticsDataFetchers.ts — the ~40 inline data-loading/fetching functions (~800 lines)
• useCodeIntelligence.ts enhancements — code smells, health score functions (~200 lines)

[mrveiss]

Closed via PR #2253 merge to Dev_new_gui.