feat(#171): Implement chat command parsing

Add command parsing layer for chat integration (Discord, Mattermost, Slack).

Features:
- Parse @mosaic commands with action dispatch
- Support 3 issue reference formats: #42, owner/repo#42, full URL
- Handle 7 actions: fix, status, cancel, retry, verbose, quiet, help
- Comprehensive error handling with helpful messages
- Case-insensitive parsing
- Platform-agnostic design

Implementation:
- CommandParserService with tokenizer and action dispatcher
- Regex-based issue reference parsing
- Type-safe command structures
- 24 unit tests with 100% coverage

TDD approach:
- RED: Wrote comprehensive tests first
- GREEN: Implemented parser to pass all tests
- REFACTOR: Fixed TypeScript strict mode and linting issues

Quality gates passed:
- ✓ Typecheck
- ✓ Lint
- ✓ Build
- ✓ Tests (24/24 passing)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/api/src/bridge/parser/command.interface.ts

@@ -0,0 +1,90 @@
+/**
+ * Command Parser Interfaces
+ *
+ * Defines types for parsing chat commands across all platforms
+ */
+
+/**
+ * Issue reference types
+ */
+export interface IssueReference {
+  /**
+   * Issue number
+   */
+  number: number;
+
+  /**
+   * Repository owner (optional for current repo)
+   */
+  owner?: string;
+
+  /**
+   * Repository name (optional for current repo)
+   */
+  repo?: string;
+
+  /**
+   * Full URL (if provided as URL)
+   */
+  url?: string;
+}
+
+/**
+ * Supported command actions
+ */
+export enum CommandAction {
+  FIX = "fix",
+  STATUS = "status",
+  CANCEL = "cancel",
+  RETRY = "retry",
+  VERBOSE = "verbose",
+  QUIET = "quiet",
+  HELP = "help",
+}
+
+/**
+ * Parsed command result
+ */
+export interface ParsedCommand {
+  /**
+   * The action to perform
+   */
+  action: CommandAction;
+
+  /**
+   * Issue reference (for fix command)
+   */
+  issue?: IssueReference;
+
+  /**
+   * Job ID (for status, cancel, retry, verbose commands)
+   */
+  jobId?: string;
+
+  /**
+   * Raw arguments
+   */
+  rawArgs: string[];
+}
+
+/**
+ * Command parse error
+ */
+export interface CommandParseError {
+  /**
+   * Error message
+   */
+  message: string;
+
+  /**
+   * Suggested help text
+   */
+  help?: string;
+}
+
+/**
+ * Command parse result (success or error)
+ */
+export type CommandParseResult =
+  | { success: true; command: ParsedCommand }
+  | { success: false; error: CommandParseError };