refactor(session): fold the session family into packages/session/

git mv the 12 packages from session-persistence/, session-projection/,
session-title/, and telemetry/ into one session/ group per the
regrouping RFC; merge the four group READMEs into one bilingual
triplet; rewrite the group segment in tsconfig references (intra-group
references shorten to ../<pkg>), tsconfig.base.json paths/globs,
knip.json keys, vitest include, gate scripts, and authored doc/note
citations; regenerate module graph, doc graphs, catalogs, and the
lockfile importer keys. No npm names change.

Full unit suite: 8779 passed; the 18 reported failures reproduce as
env flakes (ambient-proxy IPv6 tunneling, watched-dir inotify
timeouts under parallel load) — each passes in isolation with
NO_PROXY set, matching their known pre-existing behavior on master.

knip.json

@@ -283,7 +283,7 @@
         "tests/**/*.ts"
       ]
     },
-    "packages/telemetry/session-telemetry-otel": {
+    "packages/session/session-telemetry-otel": {
       "entry": [
         "tests/**/*.spec.ts",
         "tests/**/*.e2e.ts"
@@ -414,7 +414,7 @@
         "tests/**/*.ts"
       ]
     },
-    "packages/session-title/session-title-first-message-llm": {
+    "packages/session/session-title-first-message-llm": {
       "entry": [
         "tests/**/*.spec.ts",
         "tests/**/*.e2e.ts"
@@ -434,7 +434,7 @@
         "tests/**/*.ts"
       ]
     },
-    "packages/session-persistence/session-checkpoint-policy": {
+    "packages/session/session-checkpoint-policy": {
       "entry": [
         "tests/**/*.spec.ts",
         "tests/**/*.e2e.ts"