feat: UI fixes + boocontext remainders — Memory project selector, agent event toasts, codecontext→boocontext left-overs

Fixes 3 remaining UI items from the component-wiring audit:
  - Memory page: project selector dropdown (Item 1)
  - Agent events: collision_warning + agent_message toasts via sonner (Item 2)
  - Reasoning delta already wired and working (Item 3)

Also picks up uncommitted boocontext rename changes from the subagent batch:
  - synthesisPipeline.ts tier tool names updated
  - tiers.ts STANDARD_TOOL_NAMES clears old codecontext tools
  - tool-utils.ts BUILT_IN_TOOLS updated
  - .env.example / README.md reference boocontext MCP
  - ROADMAP.md boocontext entry
  - codecontext/ dir + docs/codecontext-ts-plan.md removed (already gone from tree)

.codesight/libs.md

@@ -527,19 +527,11 @@
   - function getBackgroundTaskResult: (sql, taskId, chatId) => Promise<
   - function cancelBackgroundTask: (sql, taskId) => Promise<boolean>
   - interface BackgroundTask
-- `apps/server/src/services/boocontext_client.ts`
-  - function callBoocontext: (req, log?, msg) => void
-  - interface BoocontextRequest
-  - interface BoocontextResponse
 - `apps/server/src/services/broker.ts`
   - function createBroker: (log?) => Broker
   - interface Broker
   - type Frame
   - type Listener
-- `apps/server/src/services/codecontext_client.ts`
-  - function callCodecontext: (req, fetcher) => Promise<CodecontextResponse>
-  - interface CodecontextRequest
-  - interface CodecontextResponse
 - `apps/server/src/services/coder-notify.ts` — function notifyCoderClose: (kind, id, log?, 'debug'>, fetcher) => Promise<boolean>, type CoderCloseKind
 - `apps/server/src/services/compaction.ts`
   - function usable: (contextLimit) => number
@@ -825,34 +817,6 @@
   - type SubagentStatusInputT
   - type SubagentResultInputT
   - _...6 more_
-- `apps/server/src/services/tools/codecontext/factory.ts` — function makeCodecontextTool: (opts, unknown>;
-  mapArgs) => void
-- `apps/server/src/services/tools/codecontext/get_code_health.ts`
-  - function executeGetCodeHealth: (input, projectPath) => Promise<string>
-  - type GetCodeHealthInputT
-  - const GetCodeHealthInput
-  - const getCodeHealth: ToolDef<GetCodeHealthInputT>
-- `apps/server/src/services/tools/codecontext/get_code_impact.ts`
-  - function executeGetCodeImpact: (input, projectPath) => Promise<CodecontextResponse>
-  - type GetCodeImpactInputT
-  - const GetCodeImpactInput
-  - const getCodeImpact: ToolDef<GetCodeImpactInputT>
-- `apps/server/src/services/tools/codecontext/get_code_map.ts`
-  - function executeGetCodeMap: (input, projectRoot) => Promise<CodeMapResponse>
-  - interface CodeMapResponse
-  - type GetCodeMapInputT
-  - const GetCodeMapInput
-  - const getCodeMap: ToolDef<GetCodeMapInputT>
-- `apps/server/src/services/tools/codecontext/get_type_info.ts`
-  - function executeGetTypeInfo: (input, _projectPath?) => Promise<CodecontextResponse>
-  - type GetTypeInfoInputT
-  - const GetTypeInfoInput
-  - const getTypeInfo: ToolDef<GetTypeInfoInputT>
-- `apps/server/src/services/tools/codecontext/get_wiki_article.ts`
-  - function executeGetWikiArticle: (input, projectPath) => Promise<string>
-  - type GetWikiArticleInputT
-  - const GetWikiArticleInput
-  - const getWikiArticle: ToolDef<GetWikiArticleInputT>
 - `apps/server/src/services/tools/execute-command.ts`
   - function executeRunCommand: (input, projectRoot) => Promise<RunCommandOutput>
   - type RunCommandInputT