feat: add iterator flashcards, sync script, and project scaffolding

- iterator.org: C++ iterator flashcard deck
- questions.org: LeetCode question index (217, 242)
- inbox.org: learning inbox with two-sum implementation and notes
- sync-anki.sh: batch sync org files to Anki via emacsclient
- AGENTS.md: conventions for AI agents working in this repo

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

inbox.org

@@ -0,0 +1,59 @@
+#+title: Inbox
+* 1. two sum
+#+begin_src c++
+class Solution {
+public:
+  vector<int> twoSum(vector<int> &nums, int target) {
+    vector<pair<int, int>> rev;
+    // Fix 1 & 2: Loop over nums.size() and push nums[i]
+    for (int i = 0; i < nums.size(); i++) {
+      rev.push_back({nums[i], i});
+    }
+
+    std::sort(rev.begin(), rev.end());
+
+    for (int i = 0; i < rev.size(); i++) {
+      int want = target - rev[i].first;
+      // Fix 3: Pass the SORTED vector 'rev' to the search
+      int j = bs(rev, want, i + 1);
+      if (j >= 0) {
+        int a = rev[i].second;
+        int b = rev[j].second;
+        return vector<int>{min(a, b), max(a, b)};
+      }
+    }
+    return {};
+  }
+
+  // Updated to handle vector of pairs
+  using PairIter = vector<pair<int, int>>::iterator;
+
+  PairIter lower_bound(PairIter l, PairIter r, int target) {
+    while (l < r) {
+      PairIter mid = l + (r - l) / 2;
+      if (mid->first >= target) { // Access value via .first or ->first
+        r = mid;
+      } else {
+        l = mid + 1;
+      }
+    }
+    return l;
+  }
+
+  int bs(vector<pair<int, int>> &indexedNums, int target, int offset) {
+    auto it =
+        lower_bound(indexedNums.begin() + offset, indexedNums.end(), target);
+    if (it == indexedNums.end() || it->first != target) {
+      return -1;
+    }
+    return it - indexedNums.begin();
+  }
+};
+#+end_src
+
+~using PairIter = vector<pair<int, int>>::iterator;~
+what is using?
+
+we need to write binary search, lower bound search
+
+learn about binary search functions the natural one by god