Add 13 new grammar notes with 1010 exercises from video extraction

Scraped a 4h Spanish fundamentals YouTube video (transcript + OCR on
14810 frames), extracted structured content across 52 chapters, and
generated fill-in-the-blank quizzes for every grammar topic.

- 13 new GrammarNote entries (articles, possessives, demonstratives,
  greetings, poder, al/del, prepositional pronouns, irregular yo,
  stem-changing, stressed possessives, present/future perfect, present
  indicative conjugation)
- 1010 generated exercises across all 36 grammar notes (new + existing)
- Fix tense guide parser to handle unnumbered *Usages* blocks
- Rewrite 6 broken tense guide bodies (imperative, subj pluperfect,
  subj future) with numbered usage format
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Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/spanish-fundamentals/notes/19-combining-dops-iops.md

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+# 19. Combining DOPs & IOPs
+
+> Source: [video link](https://youtube.com/watch?v=YHDZSHCt1DE&t=4570s)
+
+When a sentence uses both an indirect and a direct object pronoun, Spanish places the **indirect object pronoun first**. If both pronouns begin with **l-** (i.e., **le/les + lo/la/los/las**), the indirect pronoun changes to **se** to avoid the cacophonous repeated L sound.
+
+## Key Rules
+- **Order:** IOP comes **before** DOP. (Mnemonic: "ID" — Indirect, then Direct.)
+- Both pronouns sit **before** the conjugated verb, OR both attach to the **end** of an infinitive/gerund (never split).
+- If two pronouns both start with **l-** (le/les + lo/la/los/las), the IOP becomes **se**:
+  - le + lo → **se lo**
+  - le + la → **se la**
+  - les + los → **se los**
+  - les + las → **se las**
+- When attaching both pronouns to an infinitive or gerund, **a written accent is required** to preserve the original stress: *comprándotelo, hacérselo*.
+- Because **se** is ambiguous, a clarifying *a + él / a ella / a usted / a Juan / a ellos / a ellas / a ustedes* is usually added.
+
+## Conjugation / Pattern Tables
+
+### Order: IOP + DOP
+
+| IOP | DOP | Combined |
+|---|---|---|
+| me | lo/la/los/las | me lo, me la, me los, me las |
+| te | lo/la/los/las | te lo, te la, te los, te las |
+| le → **se** | lo/la/los/las | se lo, se la, se los, se las |
+| nos | lo/la/los/las | nos lo, nos la, nos los, nos las |
+| os | lo/la/los/las | os lo, os la, os los, os las |
+| les → **se** | lo/la/los/las | se lo, se la, se los, se las |
+
+### Placement options
+
+| Construction | Before verb | Attached |
+|---|---|---|
+| Simple verb | Ella me lo da. | — |
+| Modal + infinitive | Yo te lo puedo comprar. | Yo puedo comprártelo. |
+| Progressive (gerund) | Yo te lo estoy comprando. | Yo estoy comprándotelo. |
+| With se + clarification | Ella se lo hace a él. | Ella quiere hacérselo a él. |
+
+## Examples
+
+| Spanish | English |
+|---------|---------|
+| Yo te lo compro. | I buy it for you. |
+| Ella me lo da. | She gives it to me. |
+| Ella me lo está dando. / Ella está dándomelo. | She is giving it to me. |
+| Tú nos la estás mostrando. / Tú estás mostrándonosla. | You are showing it to us. |
+| Ellos te los quieren presentar. / Ellos quieren presentártelos. | They want to present them to you. |
+| Ella se lo hace a él. | She makes it for him. |
+| Ella quiere hacérselo a él. | She wants to make it for him. |
+| Ella se lo escribe a él / a ella / a ellos. | She writes it to him / her / them. |
+| Tú se los lees a ellos. | You read them to them. |
+| Yo se lo estoy comprando a ellos. / Yo estoy comprándoselo a ellos. | I am buying it for them. |
+| Yo se lo puedo hacer a él. / Yo puedo hacérselo a él. | I can do it for him. |
+
+## Notes & Gotchas
+- The **se** here is **not reflexive** — it is just le/les disguised to avoid two L-pronouns in a row.
+- Because **se** can mean "to him / to her / to you (Ud./Uds.) / to them," include an *a + clarifier* for clarity.
+- When **both** pronouns attach to an infinitive that has only one syllable of stress (like *dar, ver*), you may not need the accent on the verb itself — but typically the result still needs an accent (e.g., *dárselo*).
+- Pronouns are always attached together; you cannot put one before the verb and the other on the infinitive.