feat: add HTTP transport mode alongside stdio

Adds `--http` flag (and `CODEBASE_CONTEXT_HTTP=1` env var) to run the
MCP server as a long-lived HTTP process using StreamableHTTPServerTransport.

- src/server/factory.ts: server factory so both stdio and HTTP can
  create fresh Server instances sharing the same module-level state
- src/server/http.ts: full HTTP server with per-session Server+Transport,
  session map, idle timeout reaper, and graceful shutdown
- src/index.ts: export registerHandlers, add startHttp() entry point,
  port flag parsing (--port / CODEBASE_CONTEXT_PORT, default 3100),
  fix resolveRootPath() to skip --http/--port flags

Multi-session support: each client gets its own Server+Transport while
sharing project state. stdio mode unchanged; 312/312 tests pass.

Author: PatrickSys

.codebase-context/memory.json

@@ -246,5 +246,86 @@
     "reason": "Auto-extracted from git commit history",
     "date": "2026-02-15T13:04:10.000Z",
     "source": "git"
+  },
+  {
+    "id": "0c5271f19670",
+    "type": "gotcha",
+    "category": "conventions",
+    "memory": "fix: prevent orphaned processes via stdin/ppid/onclose lifecycle guards (#77)",
+    "reason": "Auto-extracted from git commit history",
+    "date": "2026-03-19T22:09:36.000Z",
+    "source": "git"
+  },
+  {
+    "id": "76f3e2ea45ac",
+    "type": "gotcha",
+    "category": "conventions",
+    "memory": "fix: make exclude patterns recursive to prevent index pollution (#76)",
+    "reason": "Auto-extracted from git commit history",
+    "date": "2026-03-18T22:06:13.000Z",
+    "source": "git"
+  },
+  {
+    "id": "391c1d465544",
+    "type": "gotcha",
+    "category": "conventions",
+    "memory": "fix: route MCP requests per project root (#65)",
+    "reason": "Auto-extracted from git commit history",
+    "date": "2026-03-07T15:37:13.000Z",
+    "source": "git"
+  },
+  {
+    "id": "47fcd92fbcce",
+    "type": "gotcha",
+    "category": "conventions",
+    "memory": "fix: restore npx installs for published package",
+    "reason": "Auto-extracted from git commit history",
+    "date": "2026-03-05T22:24:47.000Z",
+    "source": "git"
+  },
+  {
+    "id": "6cdf7384165a",
+    "type": "gotcha",
+    "category": "conventions",
+    "memory": "fix(get-team-patterns): filter out legacy testing framework categories from patterns",
+    "reason": "Auto-extracted from git commit history",
+    "date": "2026-03-05T19:26:03.000Z",
+    "source": "git"
+  },
+  {
+    "id": "53c234c99d00",
+    "type": "gotcha",
+    "category": "conventions",
+    "memory": "fix(git): run tests only on pre-push",
+    "reason": "Auto-extracted from git commit history",
+    "date": "2026-03-05T19:16:04.000Z",
+    "source": "git"
+  },
+  {
+    "id": "ac6653e45758",
+    "type": "gotcha",
+    "category": "conventions",
+    "memory": "fix(git): tighten pre-push formatting enforcement",
+    "reason": "Auto-extracted from git commit history",
+    "date": "2026-03-05T18:47:36.000Z",
+    "source": "git"
+  },
+  {
+    "id": "cc519240e73c",
+    "type": "gotcha",
+    "category": "conventions",
+    "memory": "fix(cli): remove unused MetadataDependency import",
+    "reason": "Auto-extracted from git commit history",
+    "date": "2026-03-05T18:23:48.000Z",
+    "source": "git"
+  },
+  {
+    "id": "9f949cc7137e",
+    "type": "gotcha",
+    "category": "conventions",
+    "memory": "fix(cli): formatter audit — render missing metadata fields, README callers qualifier",
+    "reason": "Auto-extracted from git commit history",
+    "date": "2026-03-05T18:17:37.000Z",
+    "source": "git"
   }
 ]

.gitignore

@@ -23,7 +23,7 @@ nul
 .planning-archive/*
 .codex/
 grammars/*.wasm
-
+.agents/
 .tmp-research-repos/
 docs/visuals.md
 .repolore/