refactor: major codebase cleanup - BDD comments, file splitting, bug fixes (#1350)

* style(tests): normalize BDD comments from '// #given' to '// given'

- Replace 4,668 Python-style BDD comments across 107 test files
- Patterns changed: // #given -> // given, // #when -> // when, // #then -> // then
- Also handles no-space variants: //#given -> // given

* fix(rules-injector): prefer output.metadata.filePath over output.title

- Extract file path resolution to dedicated output-path.ts module
- Prefer metadata.filePath which contains actual file path
- Fall back to output.title only when metadata unavailable
- Fixes issue where rules weren't injected when tool output title was a label

* feat(slashcommand): add optional user_message parameter

- Add user_message optional parameter for command arguments
- Model can now call: command='publish' user_message='patch'
- Improves error messages with clearer format guidance
- Helps LLMs understand correct parameter usage

* feat(hooks): restore compaction-context-injector hook

- Restore hook deleted in cbbc7bd0 for session compaction context
- Injects 7 mandatory sections: User Requests, Final Goal, Work Completed,
  Remaining Tasks, Active Working Context, MUST NOT Do, Agent Verification State
- Re-register in hooks/index.ts and main plugin entry

* refactor(background-agent): split manager.ts into focused modules

- Extract constants.ts for TTL values and internal types (52 lines)
- Extract state.ts for TaskStateManager class (204 lines)
- Extract spawner.ts for task creation logic (244 lines)
- Extract result-handler.ts for completion handling (265 lines)
- Reduce manager.ts from 1377 to 755 lines (45% reduction)
- Maintain backward compatible exports

* refactor(agents): split prometheus-prompt.ts into subdirectory

- Move 1196-line prometheus-prompt.ts to prometheus/ subdirectory
- Organize prompt sections into separate files for maintainability
- Update agents/index.ts exports

* refactor(delegate-task): split tools.ts into focused modules

- Extract categories.ts for category definitions and routing
- Extract executor.ts for task execution logic
- Extract helpers.ts for utility functions
- Extract prompt-builder.ts for prompt construction
- Reduce tools.ts complexity with cleaner separation of concerns

* refactor(builtin-skills): split skills.ts into individual skill files

- Move each skill to dedicated file in skills/ subdirectory
- Create barrel export for backward compatibility
- Improve maintainability with focused skill modules

* chore: update import paths and lockfile

- Update prometheus import path after refactor
- Update bun.lock

* fix(tests): complete BDD comment normalization

- Fix remaining #when/#then patterns missed by initial sed
- Affected: state.test.ts, events.test.ts

---------

Co-authored-by: justsisyphus <justsisyphus@users.noreply.github.com>

src/features/mcp-oauth/dcr.test.ts

@@ -27,7 +27,7 @@ function createStorage(initial: ClientCredentials | null):
 
 describe("getOrRegisterClient", () => {
   it("returns cached registration when available", async () => {
-    // #given
+    // given
     const storage = createStorage({
       clientId: "cached-client",
       clientSecret: "cached-secret",
@@ -36,7 +36,7 @@ describe("getOrRegisterClient", () => {
       throw new Error("fetch should not be called")
     }
 
-    // #when
+    // when
     const result = await getOrRegisterClient({
       registrationEndpoint: "https://server.example.com/register",
       serverIdentifier: "server-1",
@@ -47,7 +47,7 @@ describe("getOrRegisterClient", () => {
       fetch: fetchMock,
     })
 
-    // #then
+    // then
     expect(result).toEqual({
       clientId: "cached-client",
       clientSecret: "cached-secret",
@@ -55,7 +55,7 @@ describe("getOrRegisterClient", () => {
   })
 
   it("registers client and stores credentials when endpoint available", async () => {
-    // #given
+    // given
     const storage = createStorage(null)
     let fetchCalled = false
     const fetchMock: DcrFetch = async (
@@ -85,7 +85,7 @@ describe("getOrRegisterClient", () => {
       }
     }
 
-    // #when
+    // when
     const result = await getOrRegisterClient({
       registrationEndpoint: "https://server.example.com/register",
       serverIdentifier: "server-2",
@@ -96,7 +96,7 @@ describe("getOrRegisterClient", () => {
       fetch: fetchMock,
     })
 
-    // #then
+    // then
     expect(fetchCalled).toBe(true)
     expect(result).toEqual({
       clientId: "registered-client",
@@ -110,7 +110,7 @@ describe("getOrRegisterClient", () => {
   })
 
   it("uses config client id when registration endpoint missing", async () => {
-    // #given
+    // given
     const storage = createStorage(null)
     let fetchCalled = false
     const fetchMock: DcrFetch = async () => {
@@ -121,7 +121,7 @@ describe("getOrRegisterClient", () => {
       }
     }
 
-    // #when
+    // when
     const result = await getOrRegisterClient({
       registrationEndpoint: undefined,
       serverIdentifier: "server-3",
@@ -133,19 +133,19 @@ describe("getOrRegisterClient", () => {
       fetch: fetchMock,
     })
 
-    // #then
+    // then
     expect(fetchCalled).toBe(false)
     expect(result).toEqual({ clientId: "config-client" })
   })
 
   it("falls back to config client id when registration fails", async () => {
-    // #given
+    // given
     const storage = createStorage(null)
     const fetchMock: DcrFetch = async () => {
       throw new Error("network error")
     }
 
-    // #when
+    // when
     const result = await getOrRegisterClient({
       registrationEndpoint: "https://server.example.com/register",
       serverIdentifier: "server-4",
@@ -157,7 +157,7 @@ describe("getOrRegisterClient", () => {
       fetch: fetchMock,
     })
 
-    // #then
+    // then
     expect(result).toEqual({ clientId: "fallback-client" })
     expect(storage.getLastSet()).toBeNull()
   })